Finally, the markedly increased risk of death (8-fold) of high AREG mRNA in KRAS mutant versus KRAS wild-type CRC patients in multivariate analysis could be explained if AREG is viewed as a protein regulated by KRAS-dependent transcription factors: the former group includes tumours bearing KRAS mutations with a markedly pro-survival, proliferative activating effect, whereas the latter group includes KRAS wild type tumours addicted to active EGFR signalling that is amenable to abrogation by cetuximab. This evidence concerns the gene KRAS and colorectal carcinoma.