MDM2 and neuroblastoma: In addition, USP7 depletion led to decreased expression of both MDM2 and EZH2 and an increase in p53 protein expression (Figure 6C,D), similar to that seen with pharmacologic inhibition of USP7 and further supporting a role for USP7 in NB tumor growth via to its effect on USP7 deubiquitinase activity, allowing for target protein degradation.