FGFR3 and rhabdomyosarcoma: To accurately assess the biological features and therapeutic potential of Surv.m-CRAs against CSCs, in a previous study we identified FGFR3 as a useful marker that allows accurate monitoring and purification of RSCs; a single implanted FGFR3-positive rhabdomyosarcoma cell could form a tumor in vivo, whereas FGFR3-negative cells did not form tumors [7].