Further analysis demonstrated that Npas4 was necessary for the protective effect of CSD since F-11 cells (a fusion product of embryonic rat dorsal root ganglion (DRG) cells with a mouse neuroblastoma cell line N18TG-2) treated with RNA interference (RNAi) against Npas4 were shown to be more susceptible to potassium cyanide (KCN)-induced cell death [23]. This evidence concerns the gene NPAS4 and neuroblastoma.