CD274 and neoplasm: Functional studies are also required to elucidate the role of M-MDSCs in tumor immune regulation, including assessing PD-1/PD-L1 expression on M-MDSCs, evaluating their immunosuppressive capacity, and analyzing the secretion of immunosuppressive and pro-inflammatory cytokines such as IL-10, IL-6, and TGF-β through single-cell sequencing and flow cytometry (39).