CXCL12 and prostate cancer: For instance, a CAF-targeting nanoparticle siRNA delivery system whereby FAPα antibody is loaded onto cell-penetrating peptide (CPP)-based nanoparticles to deliver siRNAs targeting the CAF-derived chemokine CXCL12 is reported to significantly inhibit tumor cell migration, invasion and angiogenesis in xenografts where PC-3 prostate cancer cells and FAP+ CAFs were co-engrafted orthotopically into nude mice [284,287,289,300].