SOX4 and rhabdomyosarcoma: In addition to the MET-related gene expression signature, the increase in rhabdomyosarcoma CSC number during serial xenotransplantation correlated with the upregulation of a typical EMT-inducing gene, ZEB1, and a stemness-associated gene, SOX4, which has recently been identified as a master inducer of EMT, controlling several EMT-relevant genes [46,66].