CXCL12 and osteosarcoma: Fifteen cases of primary osteosarcoma were analyzed for established markers associated with CAR cells (LEPR, EBF3, CXCL12, PDGFRA) and subdivided into low‐grade parosteal (7/16) or high‐grade intramedullary (9/16) tumors (Fig. 1, Table 1).