CDKN1A and central nervous system cancer: Although miR-10b regulation of E2F1 transcription occurs only in a subset of cultured glioma cell lines, the generally high levels of p21 expression in the majority of human GBM tumors [11–13], and significant positive correlations between the levels of numerous E2F-regulated genes and miR-10b in TCGA, suggest that this mechanism is widespread in GBM.