PDE4DIP and glioblastoma: DNA methylation analysis showed that in GBM, COAD, LUSC, PAAD, HNSC, LGG, UCEC, and BLCA patients, PDE4DIP expression was significantly positively related to DNA methylation, while was significantly negatively related to DNA methylation in STAD, KIRC, SARC, MESO, THCA, THYM, PCPG, and UVM patients (Figure S2b).