CD274 and neoplasm: Notably, PD-L1, an immune checkpoint protein expressed in melanoma cells (PD-L1 + Mel-A+) in brain tissues, was significantly decreased in dLGG–10 (44 ± 10 cells), Lipo-DOX–2 (76 ± 6 cells), and dLGG–10 + Lipo-DOX–2 (35 ± 2 cells)-treated mice compared with the tumor control (343 ± 9 cells) (Figure 3b).