TGFB1 and neoplasm: For example, CAFs can arise from resident fibroblasts and become activated in response to the release of growth factors such as TGF-β to acquire a tumour-promoting function.2 This process triggers a series of intercellular feedback loops: tumour cells recruit and activate stromal cells; these stromal cells contribute to the increased production and secretion of ECM, which, in turn, stimulates tumour progression.