Given the known links between cell-cycle regulation in division and differentiation in the developing nervous system and in neuroblastoma,23,32–34 we first investigated the effects of the CDK4/6 inhibitor PB on ADRN-type neuroblastoma cell lines SK-N-BE(2)C, IMR-32, and SH-SY5Y. The gene discussed is CDK4; the disease is neuroblastoma.