According to some studies, the preferential overexpression of nicotinamide N-methyltransferase (NNMT) in GSC, a cytosolic enzyme involved in the biotransformation of many xenobiotics, causes the exhaustion of the methyl donor S-adenosyl methionine (SAM), with consequent hypomethylation of the GB DNA, causing the translation of the tumor towards a mesenchymal phenotype and accelerating its growth [11,12]. Here, NNMT is linked to neoplasm.