CXCR4 and prostate cancer: First, they indicate that prostate cancer-associated fibroblasts (CAFs) can function as upstream hubs that secrete paracrine mediators—including TGF-β, the CXCL12–CXCR4 axis, VEGF-A, IL-6, and IL-17A—that promote extracellular matrix remodeling, angiogenesis, epithelial plasticity, metastasis, and immune exclusion.