The resistance of GBM cells to chemo- and radiotherapy has recently been attributed to the overexpression of the G2 checkpoint kinase Wee1.18 We have shown that HDAC inhibition alters the expression of two G2 checkpoint kinases, Wee1 and Chk1, and results in cells entering mitosis before DNA-damage repair. This evidence concerns the gene CHEK1 and glioblastoma.