Only a few kn^KN4 homozygous mutants survive to late embryonic stages.

The dendritic arbors of single class IV da neurons homozygous for kn^KN4 (generated by the MARCM system) are less elaborate and show decreased size compared with wild-type.

Homozygous small clones (induced in the mid-third larval instar stage) result in ectopic vein material in the wing only if the clones are located between wing veins 3 and 4. The ectopic vein material often extends outside the clone, indicating non-autonomy.

Homozygous kn^KN4 larvae consistently exhibit head defects. They lack ventral arms and have foreshortened lateralgrate. The hypopharyngeal lobe is also missing in these larvae.

Embryonic segmentation is normal. Transheterozygotes with kn¹ enhance the kn¹ wing vein phenotype, the veins are extensively fused. This loss of intervein region reduced the length and width of the wings by 80-90%. The transition point between socketed and unsocketed bristles at the wing margin is shifted posteriorly to the shifted position of wing vein L3. Germline clones give rise to fully viable offspring when outcrossed to kn⁺ sperm and does not alter the larval lethality when fertilised with kn^KN1, kn^KN2, kn^KN3 or kn^KN4 sperm. Clones generated in adult cuticle are normal unless induced in the anterior compartment of the wing in the intervein region between veins L3 and L4. Clones obey the A-P compartment boundary but when they are induced along the boundary the result is an ectopic or shifted vein with an associated loss of vein L4 in the non-mutant posterior compartment. Clones located at the wing margin generated terminal vein 3 bristles rather than true marginal bristles.