NOTCH1 and B-cell chronic lymphocytic leukemia: Indeed, CLL cells cultured in the presence of an antibody blocking the IFN-γ receptor showed a significantly downregulation of PD-L1 (Fig. 5g), which was still significantly higher than PD-L1 levels of EV-control cells, indicating that this pathway only partly contributes to the NOTCH1-mediated upregulation of PD-L1.