TGFB1 and neoplasm: Prior to tumor initiation and during the early stage of progression, TGF-β acts as a tumor suppressor via cell cycle arrest and the induction of apoptosis; however, at advanced stages, TGF-β often acts as a tumor promoter via the acceleration of the EMT, invasion, and angiogenesis, the maintenance of tumor stem cells, and the alteration of the tumor microenvironment [61].