The epithelial-mesenchymal transition (EMT) is blocked in mutant wings following eclosion, but the programmed cell death which is seen in wild-type wings during wing maturation, still occurs in the mutant flies.

The programmed cell death which is seen in wild-type wings during wing maturation after eclosion still occurs in rk¹/rk⁴ and rk⁴/Df(2L)BSC253 flies.

Fewer apoptotic B[[AG]] neurons are seen in the central ganglia of rk⁴ mutants analysed 6 hours after eclosion, compared to controls. At 24 hours after eclosion, over one-third of B[[AG]] neurons were still present in the mutant adults, compared to only 2% in controls.

Body colour: homozygous flies show a delay in post-ecdysial tanning; 3 hours after eclosion, homozygous flies have not begun to darken, whereas wild-type flies have a tanned cuticle, while by 6-9 hours after eclosion the difference is no longer apparent. Homozygotes show no difference in the time course of development from the white puparium stage onwards when compared to wild-type flies. 17% of homozygotes show a flattening of the tarsi and 100% of homozygotes fail to expand their wings. Homozygotes are much more active over the first 30 minutes after eclosion compared to wild-type flies, repeatedly alternating between cleaning and walking. They do not show air swallowing behaviour or the sustained abdominal contraction characteristic of wing expansion.

Wings unexpanded, spread and drooping. Posterior legs malformed. Both sexes fully viable and fertile. rk⁴ male mates with wild-type female only if wings removed from female. Viability 60% of wild type.