TGFB1 and neoplasm: Moreover, in response to ECM stiffness, integrin αvβ6 and αvβ8 on cancer-associated fibroblasts (CAFs) are essential to tumor metastasis by activating latent TGF-β1, and promoting the expression of and communication with CAF-related substances, such as platelet-derived growth factor receptor α or β (PDGFRα/β) and pro-inflammatory cytokines (Brown & Marshall, 2019).