IL17A and cancer: However, since identified as the requisite cytokine in combination with interleukin (IL)-6 for the differentiation of IL-17-producing CD4+ T helper cell (TH17) through inducing a master transcription factor, retinoic acid-related orphan receptor-γt (RORγt) and IL-17 (refs 3, 4), context-dependent multidirectional roles of TGF-β have been highlighted in immune regulation, similarly to its roles in carcinogenesis and cancer progression5.