Mbs^T541/+ reduces the frequency of embryonic lethality in Patj^Δ1 homozygotes from 28 to 12%. In addition, the cuticle defects seen in Patj^Δ1 embryos are strongly decreased in frequency in the Mbs^T541/+ background. Patj^Δ1/Mbs^T541 Patj^Δ1 pupae start metamorphosis (reflected by elongation and remodelling of the wing disc).

Removing one copy of Mbs antagonizes the multiple wing hair formation in dsh¹/Y mutants but has no effect on the planar polarity defects. Mbs^T541 photoreceptor clones are restored to their wild-type apical location in the eye disc when discs carry one copy of the constitutively inactive sqh^{A21.T:Zzzz\FLAG} transgene. However, the amount of photoreceptor basal mislocalization is increased when eye discs carry one copy of sqh^E20.E21 (a transgene that contains two phosphomimetic mutations). The mislocalization of photoreceptors in Mbs^T541 clones is suppressed when eye discs have a zip¹/+ background. The photoreceptor localization defect is not significantly enhanced when Mbs^T541 mutant clones express rok^CAT.Scer\UAS under the control of Scer\GAL4^tub. Photoreceptors still move basally in Mbs^T541 eye disc clones with a disco¹ background. However, instead of moving toward the optic stalk, the mutant photoreceptors are found more centrally at the basal surface of the eye disc, and are concentrated at sites where many axons are present.