CTLA4 and neoplasm: Specifically, metformin inhibits mTORC1 activation-induced differentiation of naïve CD4 T cells to inducible regulatory T cells by reducing the levels of Foxp3 protein, thereby reducing the abundance of tumor-infiltrating regulatory T cells, and also downregulated effector molecules such as CTLA4 and IL-10 (Kunisada et al., 2017).