MGMT and central nervous system cancer: Furthermore, siPOOL mediated knockdown of ERK5 also sensitised resistant LN18 cells to TMZ as well as the more TMZ sensitive U87 and U-251 cells (Figure 1A), demonstrating that targeting of ERK5 could potentially potentiate TMZ cytotoxicity in both MGMT+ and MGMT− glioma cell backgrounds (Figure S1C).