Somatic mutation of fra/DCC results in increased cell division. P35-rescued fra4mutant clone cells are marked by GFP throughout this figure. Mitotic cells are marked by red anti-phosphorylated Histone H3 staining. An increased number of mitotic cells is observed in P35-rescued fra4mutant clone cells (antenna and anterior portion of the eye shown in A); fewer mitotic cells are observed in a comparable region in a wild-type disc (B). Such excess cell division does not result from overexpression of P35 alone (green, C). In D, two Elav-positive cells located in the antenna (blue, marked by arrow) display elevated phosphorylated Histone H3 levels (overlay shown at left in D, and three single channel pictures are shown at right; high magnification views of the two cells are shown in the lower panels). Clones were generated with the eyFLP driver in A and D and with the hsFLP driver in C. Discs are oriented anterior-left and dorsal upwards, except for the disc in D, in which the dorsal side is oriented approximately 35° right of top center.