Simultaneous expression of CycD^Scer\UAS.cUa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^ptc.PU in cells of the wing disc proper has no significant effect on the morphology or proliferation of the overlying peripodial membrane cells in third instar larvae.

The strong rough eye phenotype seen in flies expressing multiple copies of E2f^{dsRNA.Scer\UAS.cJa} under the control of Scer\GAL4^GMR.PU is suppressed if they are also simultaneously co-expressing both Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa.

Fat body clones co-expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^αTub84B.PP show an increase in cell size. Most of the cytoplasm is filled with mitochondria and levels of COX activity are increased.

Ets97D⁶¹³/Df(3R)ro80b suppresses the increase in cell size seen in fat body clones co-expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^αTub84B.PP.

Homozygous Ets97D^tne-1 suppresses the increase in cell size seen in fat body clones co-expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^αTub84B.PP. The increases in the amount of mitochondria in the cytoplasm and COX activity are also suppressed.

Co-expression of btl::Egfr^{Scer\UAS.T:λ\cI-DD}, Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa induces excess glia in third instar larval brains.

Co-expression of CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^fkh.PH does not prevent the salivary gland degradation that is seen during the pupal stage in normal development.

Co-expression of Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa under the control of Scer\GAL4^GMR.PF results in enlargement of the eye together with an increase in ommatidial size. Cells from third larval instar eye discs co-expressing Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa under the control of Scer\GAL4^GMR.PF are larger than wild-type controls, and there is an increase in cells in S and G[[2]/M compared to wild type.

Clones of cells in the third larval instar fat body co-expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^Act5C.PP are larger than wild-type controls and contain more DNA.

Clones of cells in the wing disc co-expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^Act5C.PP show a 60-70% increase in median clone size compared to wild-type controls.

Expression of CycD^Scer\UAS.cMa and Cdk4^Scer\UAS.cMa in the ring gland using Scer\GAL4^P0206 induces autonomous growth.

When CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa are driven by Scer\GAL4^GMR.PF mutant eyes have bigger ommatidia and a rough appearance. This phenotype is suppressed by Df(3L)Scf-R6 or Df(3L)Scf-R11, but not Df(3L)29A6. When CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa are driven by Scer\GAL4^GMR.PF, eye imaginal disc cells exhibit an average increase in cell size. This effect is suppressed by Df(3L)Scf-R6 or mRpL12¹⁰⁵³⁴. Proliferation in these cells appears normal. The eye phenotypes seen in CycD^Scer\UAS.cDa, Cdk4^Scer\UAS.cMa (driven by Scer\GAL4^GMR.PF) animals is suppressed by mRpL12¹⁰⁵³⁴. The eye phenotypes seen in CycD^Scer\UAS.cDa, Cdk4^Scer\UAS.cMa (driven by Scer\GAL4^GMR.PF) animals is suppressed by mRpL12¹⁰⁵³⁴. This suppression effect is counteracted by the addition of mRpL12^{Scer\UAS.P\T.T:Avic\GFP-EGFP}. When CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa are induced in random clones (driven by Scer\GAL4^Act5C.PP), a 60% increase in clone areas is seen. Since these cells also proliferate at an increased rate, they retain their normal size. This effect is also suppressed by mRpL12¹⁰⁵³⁴. When CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa are expressed in fat body cells additional rounds of endoreduplication are stimulated in normally fed animals and also to a greater extent in starved animals. This effect is also suppressed by mRpL12¹⁰⁵³⁴. When CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa are expressed in fat body cell or tracheal cells an apparent increase in mitochondrial activity is seen. The overgrowth defects associated with over-expression of CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa are suppressed by hypoxia and mitochondrial inhibitors.

Expression of Cdk4^Scer\UAS.cMa, under the control of Scer\GAL4^en-e16E, drives cell proliferation in hh^ts2-depleted larvae. Such larvae raised at the restrictive temperature develop larger discs than hh^ts2 larvae, but these discs still fail to form squamous cells.

Clones in the eye disc co-expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^Act5C.PP result in larger cells than normal.

Cdk4^Scer\UAS.cMa; CycD^Scer\UAS.cDa; Scer\GAL4^GMR.PF flies have enlarged ommatidia and lengthened interommatidial bristles. These phenotypes are partially suppressed by Df(3R)6-7/+, Df(3R)3-4/+, Hph^S030304/+ or Hph⁰²²⁵⁵/+ but not Df(3R)110/+. FACS analysis of dissociated eye discs from Cdk4^Scer\UAS.cMa; CycD^Scer\UAS.cDa; Scer\GAL4^GMR.PF indicates that Scer\GAL4 expressing cells are larger than non-expressing and a decreased proportion are in S-phase. The increase in cell size, but not the reduction in S-phase, is partially suppressed by Hph⁰²²⁵⁵/+. Somatic clones of Cdk4^Scer\UAS.cMa; CycD^Scer\UAS.cDa; Scer\GAL4^Act5C.PP cells in the wing disc are 75% larger than control clones 48 hours after induction at 66 hours after egg laying. This phenotype is suppressed by Hph⁰²²⁵⁵/+. The cells in these enlarged clones are not significantly larger than wild-type and do not differ significantly from wild-type controls in their cell cycle phasing. Cell size and cell cycle phasing in these clones is also unaffected bu the presence of Hph⁰²²⁵⁵/+. CycD^Scer\UAS.cDa; Cdk4^Scer\UAS.cMa; Scer\GAL4^Act5C.PP somatic clones do not grow any larger when Hph^EP3200 is present unless BacA\p35^Scer\UAS.cHa is also present, in which case the effects on growth are additive. The wings of CycD^Scer\UAS.cDa; Cdk4^Scer\UAS.cMa; Scer\GAL4^en-e16E Hph^EP3200; Scer\GAL4^en-e16E adults have an enlarged posterior compartment but no change in trichome density, indicating increased cell number without cell size change.

Somatic clones expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa (driven by Scer\GAL4^Act5C.PP, in the wing disc) are significantly larger than controls. When somatic clones expressing CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa driven by Scer\GAL4^Act5C.PP or Scer\GAL4^dpp.blk1 leads to wings that are significantly larger than wild-type.

Co-expression of Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa suppresses the inhibition of growth seen in clones in the wing discs expressing ptc^Scer\UAS.cCa under the control of Scer\GAL4^Act5C.PP.

Co-expression of both CycD^Scer\UAS.cMa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^en-e16E results in overgrowth of the posterior compartment of the wing, significantly increasing the posterior:anterior ratio by 11%. This overgrowth phenotype is unaffected by Df(3L)ban^Δ1/+. Co-expression of both CycD^Scer\UAS.cMa and Cdk4^Scer\UAS.cMa in animals expressing ex^Scer\UAS.cBa under the control of Scer\GAL4^hs.2sev increases the overall size of the eye but has little effect on the roughness and blistering.

Co-expression of CycD^Scer\UAS.cMa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^Act5C.PP results in ectopic S phase in the posterior part of the developing eye but not in the morphogenetic furrow. Co-expression of Rbf^280.Scer\UAS blocks the ectopic S phase in the eye disc caused by co-expression of CycD^Scer\UAS.cMa and Cdk4^Scer\UAS.cMa under the control of Scer\GAL4^Act5C.PP.

Expression of both Tsc1^Scer\UAS.cTa and gig^Scer\UAS.cTa in the eye under the control of Scer\GAL4^ey.PH results in a much smaller eye than normal. Coexpression of both CycD^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa fully suppresses the phenotype.

When clones expressing Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa (driven by Scer\GAL4^Act5C.PP) are examined, although there is no alteration in cell cycle phasing or cell size, there is an increase in the number of cells per clone, when compared to wild-type sister clones - indicating an accelerated cell division. Adult wings containing these clones show no gross abnormalities in overall shape, venation, bristle or trichome patterning. There are also no significant changes in cell morphology or cell density. In adult eyes that clonally overexpress Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa (under the control of Scer\GAL4^Act5C.PP), there is a striking enlargement of ommatidia. This effect is cell autonomous. There is also a mild disorganisation in the regular arrangement of ommatidia, but no specific defects in cell differentiation or overall patterning. Hypertrophy occurs in several cell types and structures, including primary pigment and cone cells, photoreceptors and interommatidial bristles. In clones in ommatidia, 5 cone cells are seen instead of the normal 4. When Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa are driven by either Scer\GAL4^hs.2sev or Scer\GAL4^GMR.PF, all ommatidia are enlarged, as is the entire eye, which bulges out in an ominous fashion. Examination of Cdk4^Scer\UAS.cMa,CycD^Scer\UAS.cDa,Scer\GAL4^GMR.PF flies reveals enlarged photoreceptor cell bodies and rhabdomeres and excessive accumulations of actin. The eye size phenotype is dose dependant in relation to CycD^Scer\UAS.cDa. When Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa are driven by either Scer\GAL4^ey.PH no eye phenotype is seen. When Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa are driven by Scer\GAL4^GMR.PF, and the cells of the eye disc analysed using FACS analysis, a significantly increased fraction of S and G2 phase cells was seen in cells from posterior to the morphogenetic furrow. Also a significant increase in cell size is seen in these posterior eye cells. Co-expression of Rbf^Scer\UAS.cDa, Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa in clones (driven by Scer\GAL4^Act5C.PP) produces cells that cycle more rapidly than cells expressing Rbf^Scer\UAS.cDa alone. Clones have fewer cells than wild-type controls, but they encompass substantially more area. Co-expression of Rbf^Scer\UAS.cDa, Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa, when driven by Scer\GAL4^hs.2sev or Scer\GAL4^GMR.PF leads to a slight eye phenotype. When driven by Scer\GAL4^ey.PH a slightly reduced eye phenotype is seen. Co-expression of Cdk4^Scer\UAS.cMa and CycD^Scer\UAS.cDa under the control of Scer\GAL4^F4, results in oversized glands with nuclei containing excessively endoreduplicated polytene chromosomes. Co-expression of Rbf^Scer\UAS.cDa and Cdk4^Scer\UAS.cMa when driven by Scer\GAL4^hs.2sev or Scer\GAL4^GMR.PF no eye phenotype is seen. When driven by Scer\GAL4^ey.PH, severely reduced eyes are seen.