CD274 and acute myeloid leukemia: To this end, MEK inhibition has also been shown to reverse PD-L1–mediated inhibition of cytotoxic T-cell function in the immunotherapy of acute myeloid leukemia cells.55 Thus, activated ERK signaling is important in allowing the upregulation of PD-L1 and MHC-I by MMC, presumably contributing to the synergistic combination of PD-L1 antibody and MMC.