VTCN1 and neoplasm: Previous studies have found that M2 macrophages with immunosuppressive properties can promote tumor immune escape by upregulation of non-classical MHC class I molecules (e.g., HLA-E and HLA-G), inhibitory ligands for T cells, apoptosis receptors (e.g., PD-L1, TRAIL, and B7-H4), and SIRP-alpha [43, 44].