PRF1 and neoplasm: In WT mice, α-PD-1 treatment showed limited efficacy, whereas in Myeloid-GAS6 KO mice, α-PD-1 treatment significantly enhanced antitumor immunity, as evidenced by reduced expression of immunosuppressive markers (CD163 and TIGIT) and increased expression of the cytotoxic marker perforin in the tumor microenvironment (Fig. 8A).