PDCD4 and central nervous system cancer: First, we analyzed the clinical glioma samples from the TCGA database and performed the Spearman’s rank correlation coefficient analysis using the XLSTAT software, and observed that the mRNA expression of AKT2, but not AKT1 or AKT3, was inversely associated with that of PDCD4 (Spearman = −0.47, P = 0.002967) (Figure 2A).