TGFB1 and glioblastoma: We also found that GBM clinical specimens expressed detectable levels of protein for CD274 (PD-L1), NT5E (CD73), ENTPD1 (CD39), LGALS1 (galectin-1), and TGFB1 but not PDCD1LG2 (PD-L2) (Figure 3L).