PRF1 and neoplasm: Notably, these GMM-mediated immune cells also produce effects on the tumor environments such as that Treg cells in tumor environment can produce vascular endothelial growth factor (VEGF) to promote angiogenesis, and inhibit T effective (Teff) cells, NK cells and antigen-presenting cells by inhibitory cytokines such as IL-10 and cytotoxic molecules such as granzymes and perforin, which can directly kill Teff cells and antigen-presenting cells.75