Cdc421/+ fly eyes do not show R-cell loss or ommatidial rotation defects (planar cell polarity-like defects).
12% of flies heterozygous for Cdc421 exhibit extra crossveins. Cdc421/Cdc425 mutant eyes display disruptions in the normal ommatidial pattern, ommatidial fusion, and loss of bristles in the dorsal posterior quadrant. All photoreceptor cells are present within the ommatidia and in the proper orientation. Cdc421/Cdc425 mutant wings often have extra anterior crossveins. Somatic Cdc421 clones in the follicle cells leads to the loss of columnar cell shape, formation of multiple layers of cells at the posterior end of the egg chamber, and apparent fusion of adjacent egg chambers.