TGFB1 and neoplasm: One of the principal explanations for such observations is the fact that α‐SMA is a marker for CAFs which arise from normal fibroblasts via TGF‐β, osteopontin (OPN), interleukin‐1β (IL‐1β), PDGF, TNF‐α, and FGF signals from the tumor [43, 44].