PDPK1 and glioblastoma: IL-6 secreted by M2 macrophages promoted glycolysis of GBM cells by phosphorylating PGK1 via 3-phosphoinositide-dependent protein kinase 1 (PDPK1) (Zhang et al., 2018), and quinolinic acid secreted by microglia was taken up by glioma cells for the synthesis of NAD+ to resist oxidative stress (Sahm et al., 2013).