In mutant wings, the columnar epithelium is abnormally thin. Many cells lose their capacity to remain intergrated in the epithelium and are extruded basally to form a disorganised mass. Many apoptotic cells are seen below the epithelial layer. Some of the extruded cells are alive and appear mesenchymal, having lost their polarized epithelial character. These cells produce F-actin rich filopodia and appear to acquire motile behaviour.
Homozygous larvae show a growth defect phenotype. Mutants are delayed with respect to growth and developmental timing. After 5 days the largest mutant larvae grow to about one-third of the size of controls. Relatively few progress as far as third instar larvae. Some larvae have an abnormally long lifespan. More than 5% of mutant larvae remain alive for 15 days and some reach a relatively normal third-instar larval size. slik1/slikKG04837 animals are viable, 90% of expected flies survive. slikKG04837/slik1 flies how a 15% decrease in viability. Nearly 40% of the wings in the surviving flies have defects. Most show curvature of the wing blade surface or small isolated vesicles. However 30% of affected wings show a stronger phenotype characterised by accumulation of vesicles and reduction in wing size. These defects correlate with an increased level of apoptosis in wing discs.