TGFB1 and colorectal carcinoma: In normal tissue, it can act to block epithelial growth, while in a cancerous environment, it increases tumour cell progression.163 Mutational inactivation of TGF-β signalling via tumour-stromal interactions is a crucial player in CRC progression, and alterations in this pathway have been shown to affect 40-50% of all CRCs, which renders the epithelium resistant to the cytostatic and pro-differentiation effects of the TGF-β ligand.