These can be largely categorized into four distinct processes: (1) growth modulation, particularly escape from growth inhibition by TGF-β at the early stage of cancer initiation; (2) enhanced synthesis of the extracellular matrix and fibrosis by TGF-β in the tumor microenvironment; (3) promotion of EMT and/or metastasis by TGF-β; and (4) immune suppression by TGF-β in the tumor microenvironment. This evidence concerns the gene TGFB1 and cancer.