EGFR and glioma: Down-regulation of N-acetylgalactosaminyltransferase 2 (GALNT2) expression can inhibit the proliferation, migration and invasion of glioma cells by inhibiting O-glycosylation, phosphorylation of EGFR and its downstream PI3K/Akt/mTOR pathway, and the opposite effect is observed when GALNT2 is overexpressed (Fig. 2c) [114].