SIRT1 and neuroblastoma: For example, a nM PKC inhibitor, Ro31–8220, shows inhibitory activity against SIRT1 and SIRT2, with IC50 values of 3.5 μM against SIRT1 and 0.8 μM against SIRT2.1025 In a human neuroblastoma cell line, Ro31–8220 was found to reduce PKC activity and the tau phosphorylation pattern.1026