CDK4 and neuroblastoma: SH-SY5Y and SK-N-MC cells have been widely used in neuroblastoma research16,17and our previous study has shown NVP-BEZ235 (BEZ235), a dual PI3K and mTOR inhibitor18 declined the expression of PI3K/mTOR pathway-related proteins in both cells.19 Therefore, both cells were used to evaluate the roles and mechanism of autophagic degradation of the CDK4 on cell cycle distribution.