KRAS and colonic neoplasm: TGF-β pathway is also involved in tumorigenesis of colon cancer, as genetic inactivation of TGF-β type 1 receptor (Tgfbr1/Alk5) enhanced the ability of K-Ras (G12D/+) mutation to drive dedifferentiation and markedly accelerated tumorigenesis, which was associated with a marked activation of MAPK signaling (Cammareri et al., 2017).