Fig. 6. Eyc overexpression causes ER proliferation and inhibition of Rh1 maturation. Quantitation of ER stacks in R cells from the experiment shown in Fig. 5C,D. (A) In Hs-GAL4/+ control, the majority of R cells show two to three ER stacks per cross section, while heat shocked Hs-GAL4/UAS-eyc R cells typically show greater numbers of stacks. (B) Western blot from the parallel experiment shows the overexpression of Eyc inhibits Rh1 maturation. Protein samples were extracted from two eyes; ß-Tubulin was used as a loading control. 4C5 anti-Rh1 antibody detects a 35 kDa mature form of Rh1, levels of which are significantly reduced in Hs-GAL4/UAS-eyc fly eyes compared with Hs-GAL4/+. Additionally, higher molecular weight, immature Rh1 is more abundant in Hs-GAL4/UAS-eyc eyes than in the Hs-GAL4/+ control.