Fig. 6.

Ets21c requires JNK activity to promote invasiveness but not growth of tumors. (A-B) On day 9 AEL, ras^V12ets21c^LONG GFP-marked clones showed dramatic enrichment of MMP1 protein (A′) and filamentous actin, visualized with phalloidin (Phal; B′) in the cell cortex. Migrating cells were devoid of the differentiation marker ELAV (B″). ras^V12ets21c^LONG cells overgrew the entire EAD and spread over the brain lobes and VNC (arrowhead in A). (C) Blocking JNK (ras^V12ets21c^LONGbsk^DN) suppressed tumor invasiveness but caused even greater overgrowth of GFP⁺ clonal tissue within the EAD. (D) Quantification of tumor invasiveness confirmed the requirement of JNK signaling for dissemination of ras^V12ets21c^LONG clonal cells. Four grades of invasiveness were scored based on spreading of clonal GFP-positive cells into larval brains dissected on day 8 AEL. Results are the percentage of brains in each category with P<0.0001. (E) ras^V12ets21c^LONG mosaic EAD showed marked increase in expression of the JNK targets upd3, mmp1, dilp8 and puc, whereas cher expression was unaffected relative to control and ras^V12 mosaic EAD. Data are mean values±s.e.m.; n=3-5; ***P<0.001; **P<0.005; *P<0.01. Regulatory regions of all tested genes harbor AP-1, Ets21c and Ftz-F1 binding motifs. (A,C) show projections of multiple confocal sections, and (B) represents single sections. Scale bars: 100 µm (A-C). EAD, eye/antenna disc; BL, brain lobe; VNC, ventral nerve cord.