Whatever the actual mechanism of decreased H3K9me3 in gliomas grades 3 and 4 might be, our observation points towards this particular alteration being coincident with the late stages of gliomagenesis but is apparently at some variance with experimental findings according to which H3K9 trimethylation is thought to interfere with glial differentiation since neurosphere cultures overexpressing H3K9me3 display decreased GFAP protein. This evidence concerns the gene GFAP and central nervous system cancer.