TGFB3 and cancer: TGF-β is a potent cytokine secreted by several types of inflammatory cells and cancer cells.34 TGF-β exists in three different isoforms (TGF-β1, TGF-β2 and TGF-β3), with TGF-β1 being the most abundant isoform in cancer.35 TGF-β1 can either suppress or promote tumour growth depending on the tumour stage and its interactions with other components of the microenvironment.