MYC and neoplasm: To assess the loss-of-function effects of MYC and YBX1 on RMS tumor cell growth and sphere formation, FN RMS (RD, SMS-CTR) and FP RMS (Rh5 and Rh30) Cas9-expressing stable lines were transduced with lentiviral constructs expressing double gRNAs (dgRNA) against MYC and YBX1.