CDKN1A and glioblastoma: Conversely, there was a substantial enhancement observed in the expression level of CDK Inhibitor 1 A (CDKN1A/P21) [33] in the CARD16-sh GBM cells(Supplementary Fig. S5A), and phosphorylation of endogenous FOXO1 at Ser249 was abolished (Fig. 8A).