A signaling protein with dual personality—it suppresses inflammation and promotes tissue repair, but can also drive fibrosis and help tumors evade the immune system.Transforming growth factor beta (TGF-β) is a pleiotropic cytokine superfamily member that regulates cell growth, differentiation, apoptosis, and immune function. TGF-β signals through SMAD-dependent and SMAD-independent pathways. In early-stage disease it acts as a tumor suppressor; in advanced cancer it promotes epithelial-mesenchymal transition, metastasis, and immune evasion. In tissue repair, TGF-β drives fibroblast activation and collagen deposition—beneficial in wound healing but pathological in fibrosis.