Macrophages are transformed into an immunosuppressive M2-like phenotype characterized by increased expression of PD-L1 and IL-10 through the TLR4-mediated MyD88-P38-STAT3 signaling pathway, which inhibits the proliferation of CD4+ and CD8+ T cells in vitro and promotes tumor growth mainly through PD-L1 in vivo. This evidence concerns the gene STAT3 and neoplasm.