Our study showed the following: (1) MET activation up-regulates co-inhibitory molecules (particularly PD-L1) and down-regulates co-stimulatory molecules; (2) MET inhibition in tumor cells enhances the function of co-cultured immune cells; (3) MET expression by the tumors of cancer patients, including those with NSCLC, and in cell lines positively correlates with that of PD-L1; and (4) MET overexpression is related to immunosuppressive features in the tumor microenvironment of PD-L1high NSCLC. Here, CD274 is linked to neoplasm.