Characterization of fra mutant cells in the developing eye-antennal disc. Mutant cells are positively marked (green) in A,B,C,G,I,J,K,L,M and negatively marked by lack of GFP in D,E,F,H. During normal eye development, Elav (red in A,B,C,D,E,G,H) is detected in differentiating neurons posterior to (right of) the morphogenetic furrow (white arrowhead, A), but not in the antennal region (left of arrowhead, A). Isolated P35-rescued fra4mutant cells are found anterior to the furrow (grey arrowheads, B; cells marked by arrow are magnified in inset) and on the optic stalk (arrow, G). Expression of P35 alone (green in A, C) does not produce this phenotype. In the absence of P35-rescue, isolated fra3(GFP-negative in D,E) or fra4(GFP-negative in F) cells (arrows) expressing photoreceptor markers (Elav in D,E; Delta in F) invade the optic stalk. GFP-negative fra3mutant clones (circled) generated in the wing disc do not express Elav (H). P35-rescued fra4mutant cells (green in I,K,M) express high levels of phospho-JNK (red in I), phospho-ERK (red in M), and Mmp1 (red in K), none of which are altered by P35 alone (J,L). P35-rescued fra4mutant cells were detected with a P35 antibody (green staining in B,G,I,K) or by GFP expression (M). Control clones expressing P35 alone are marked by GFP (A,C,J,L). eyFLP was used to generate clones in B,D,F,G,I,K,M, and hsFLP was used in A,C,E,H,J, and L. Third instar eye-antennal discs are oriented anterior left and dorsal up in all panels but H, which shows the posterior ventral portion of the wing disc. The entire eye-antennal disc is shown in A and B, the optic stalk in C,D,E,F,G, and the antennal portion of the disc in I,J,K,L,M.