DPP4 and osteosarcoma: For human CXCL10 and CXCL11, the corresponding CD26-truncated isoforms CXCL10 (3–77) and CXCL11 (3–73) were previously isolated from natural sources, including conditioned medium from MG-63-osteosarcoma cells, fibroblasts and keratinocytes [22,58,59,60,61].