SMAD7 and colorectal carcinoma: Overall, our analyses suggest that genetic variation in TGF beta signaling (pathway 7), which includes members such as BMP2, BMPR2, SMAD3, and SMAD7 implicated in CRC risk by previous large case-control and GWAS reports [36,37,38], is sufficient to alter CRC risk, independent of Se status interaction, while SNP risk associations attributed to the antioxidant and apoptosis pathways may be significantly modified by Se status interactions.