ACTA1 and neoplasm: CAFs are activated stromal cells within the tumor microenvironment (TME), characterized by spindle-like morphology, α-SMA/FAP expression, and secretion of pro-tumorigenic factors (e.g., IL-6, CXCL12, TGF-β), originating from diverse sources including resident fibroblasts, mesenchymal stem cells, and transdifferentiated endothelial cells, with high functional plasticity driving TME remodeling [41,42].