In this study, we set out to investigate the ability of these three CDK4/6 inhibitors: palbociclib (PB), abemaciclib (ABE) and ribociclib (RIBO), to induce differentiation of the relapsed, high-risk MYCN-amplified neuroblastoma cell line SK-N-BE(2)C, with and without retinoic acid (RA). The gene discussed is CDK4; the disease is neuroblastoma.