Figure 8. JNK signalling in scrib⁻+ab tumours is required for invasion, but not tumour overgrowth.

ey-FLP induced eye/antennal disc clones at 5 (A,B,E,G) and 7 days (C,D,F,H) AEL. Clones are marked by GFP (white, or green in merges), and JNK signalling is indicated by β-Gal expression from the msn⁰⁶⁹⁴⁶-lacZ enhancer trap or Mmp1 expression (white, and blue in the merges). Tissue morphology is shown by F-actin (red in merges). Brain lobes in D,E,F,H are marked by BL. GFP (panels A–H), β-Gal (A′–D′), Mmp1 (E′–G′), F-actin (H′) and merges (A″–H″). (A) Control clones show the normal pattern of msn-lacZ expression in the eye antennal disc. (B) Clones overexpressing ab do not alter the normal pattern of msn-lacZ expression. (C,D) scrib¹+ab clones show ectopic expression of msn-lacZ in some cells (C), including those that are fusing with the brain lobes (D). (E,F) Mmp1 levels are elevated in scrib ¹+ab tumour cells migrating between the brain lobes (F, arrowhead), compared to control eye discs and brain lobes (E). (G) Mmp1 levels are slightly elevated in some ab-expressing clones (G, arrowheads). (H) scrib¹+ab+bsk^DN clones massively overgrow similar to scrib ¹+ab tumours, however, the eye/antennal discs do not fuse with each other or with the brain lobes, and the tumour cells show no evidence of invasive migration between the brain lobes. Yellow scale bar = 50 µm.