CD27 and neoplasm: Additionally, although in MNG cytotoxic T cell levels were higher than in GBMs, and expression of the co-stimulatory CD28 was also present in both tumor types, the mRNA levels of CD27, a member of the tumor necrosis factor (TNF) receptor superfamily and co-stimulatory immune checkpoint molecule for activated T cell survival was highly presented compared to CD28 (Figure 2B).