In glia, JNK is likely to act as a proapoptotic signal as it does in epithelia—indeed, subperineurial glial cells possess a cryptic JNK-dependent apoptotic programme.35 However, any such programme must be suppressed by survival signals from oncogenic Ras as it is in other contexts.36 We found that Mmp1 expression was JNK-dependent, supporting the idea that JNK activation is subverted by tumour cells to promote invasion. This evidence concerns the gene MAPK8 and neoplasm.