ATP6AP2 and neoplasm: To explore the relationship of the RAS pathway with the tumour microenvironment, ssGSEA was performed on the gene expression of RAS receptors (ATP6AP2, AGTR1, and AGTR2) and microenvironment pathways such as hypoxia, mature vasculature/microvasculature, stem cell plasticity, as well as the established molecular subtypes of glioblastoma (i.e., classical, mesenchymal, and proneural) [33].