CDC6 and glioblastoma: In addition, significant differences were observed in the expression of CDC6 between grade II and IV astrocytomas (p<0.0001), with a 1.38-fold increase in its relative expression in GBM samples, and between levels III and IV astrocytomas (p<0.05), with a 1.27-fold increase in its gene expression in GBM samples (Fig 2B).