CD4 and glioblastoma: Indeed, genome-wide DNA methylation analysis of tumor-infiltrating and circulating CD4+ T cells from glioblastoma (GBM) patients revealed unique DNA methylation and gene expression patterns between T cells derived from the different sources, as regards genes implicated in T-cell activation, aggregation, and chemotaxis, suggesting that the glioblastoma microenvironment may hamper the anti-tumor response by inducing significant epigenetic alterations in tumor-infiltrating T cells [160].