SMAD4 and colorectal cancer: Indeed, somatic mutations in 95 genes significantly mutated in colorectal cancer, including six known driver genes (APC, BRAF, KRAS, SMAD4, TP53, and PIK3CA; refs. 28, 29; Supplementary Table S1), were not observed in tumors from Apc mice, irrespective of the presence or absence of Dok-3.