CXCL12 and cancer: Human lung fibroblasts, especially when activated into CAFs, secrete cytokines and growth factors (like TGF‐β, IL‐6, PDGF, EGF, HGF, CXCL‐12), ECM proteins, and remodeling enzymes like MMPs and pro‐invasive signals that potentiate cancer stemness and metastasis [31, 32, 33, 34, 35].