In the study presented here, we investigated the effects of CCNB1/cdk1 knock down by siRNA and analyzed the consequences of RO-3306 mediated cdk1 inhibition as a function of variable expression of MYCN and p53 in preclinical models of embryonal tumors including neuroblastoma, medulloblastoma and rhabdomyosarcoma. The gene discussed is MYCN; the disease is medulloblastoma.