Fig. 1.

A screen to identify regulators of the cell cycle identifies Cabut. (A) Schematic of the PCNA-miniwhite⁺ reporter gene. (B–E) Drosophila carrying the PCNA-miniwhite⁺ reporter and other transgenes or mutations, with age- and sex-matched controls on the left. (B) FRT^82B ago³ mutant clones generated by ey-FLP have red eye pigmentation with PCNA-miniwhite⁺. (C) e2f2^76q1; e2f1^su89/+ mutant eyes are red with PCNA-miniwhite⁺. (D and E) LA enhancer-promoter lines predicted to express either E2f1 (LA0365) (D) or cabut (LA0930) (E) crossed to GMR-Gal4(ey-CFP); PCNA-miniwhite⁺ (Right) have increased red eye pigmentation. (F) Thirty hours APF, control eyes did not undergo ectopic mitoses (anti-PH3 immunostaining, red) and showed no PCNA-GFP expression (F′). (G and H) Thirty hours APF, eyes and wings with cbt expression by GMR-Gal4 and en-Gal4, respectively, demonstrated ectopic mitoses (red, G and H) and PCNA-GFP expression (green, G′ and H′). Arrows in G indicated the mitotic (PH3⁺) cells. “A” and “P” shown in (H and H′) marked the anterior and posterior compartments of the pupal wing. Nuclei were stained with Hoechst (blue) in F, G, and H. (Scale bars, 50 μm.)