Fig. 4. Ras is required for the viability of PM cells. (A-C) hsFLP; P[FRT] Ras¹ Ubi-GFP /P[FRT]82B f⁺ wing disc with Ras¹/Ras¹ mitotic clones in the PM. Ras¹/Ras¹ cells are marked with GFP (A). The disc is also stained for DAPI (B). C is the merge of A and B. Note that the clones are degenerating (note speckled pattern of GFP expression) and are occupied by surrounding normal cells. The regions without GFP expression represent Ras⁺/Ras⁺ cells (twin of Ras¹/Ras¹ clones), which survive normally. (D) ap-GAL4/UAS-nuclear lacZ wing disc stained for ß-galactosidase and Wg expression. ap-GAL4 is expressed in the entire dorsal compartment. (E) ap-GAL4/UAS-Dras1^N17 wing disc stained for Wg expression. Note severe reduction in the notum size. (F) ap-GAL4/UASDras1^N17; UAS-P35. DN-Ras-induced reduction in notum is partially rescued by P35.