RIPK1 and central nervous system cancer: Treatment of U251 glioma cells with the RIPK1 kinase inhibitors Nec-1 or the MLKL oligomerization and membrane translocation inhibitor necrosulfonamide (NSA), respectively, had no significant impact on cellular growth (Fig. 3A), indicating that the pro-proliferative role of RIPK1 is kinase-independent.