Colonic and rectal tumor progression is further promoted by inactivating mutations in the TP53 gene, activating mutations of KRAS leading to constitutive activation of the epidermal growth factor (EGF) pathway, and inactivating mutations of SMAD4 resulting in the shut-down of the proliferation inhibitory canonical pathway of transforming growth factor (TGF)-β [27,28,29,30]. Here, EGF is linked to rectal neoplasm.