CD274 and central nervous system cancer: Here, we have decided to focus our study on four main actors of the immune escape of glioma cells: PD-L1 (since PD-L1 is upregulated in glioma [24]), Fas (a crucial player of the immune system-induced apoptosis [25]), DcR3 (a negative regulator of Fas [26]), and LLT1 (since LLT1 acts as a mediator of immune escape [27]).