MAPK3 and glioblastoma: In glioblastoma cell lines, activation of ERK1/2 by epithelial growth factor (EGF) leads to the nuclear translocation of pyruvate kinase M2 (PKM2), a critical enzyme involved in the production of pyruvate in the glycolysis pathway, leading to a positive feedback loop that ultimately results in an increase in aerobic glycolysis [42].