Using a puckered enhancer trap (puc-lacZ and puc-Gal4) as readout for JNK activity, we found that JNK signalling was induced in enterocytes surrounding Sox21a tumours from Sox21a flies or flies with EB-specific depletion of Sox21a by RNAi (Fig. 7a,b). Here, MAPK8 is linked to neoplasm.