To assess the likely contribution of direct versus indirect effects on the actin cytoskeleton, we tested the effect of a dominant-negative version of Mal (malDN), which lacks its C-terminal transcription activation domain.34 Compared to RasV12/pico control animals, there was a significant reduction in the number of cases of tumour invasion in siblings coexpressing malDN (82/100 to 52/100 cases, respectively; Fisher’s exact test, P<0.0001). This evidence concerns the gene MAL and neoplasm.