IL2 and neoplasm: This promotes T cell apoptosis and inhibits the proliferation of T cells and secretion of cytokines such as IL-2 (Fig. 4).176,177 In addition, PD-1 can also activate PTEN, indirectly inhibiting the TCR-mediated PI3K/AKT signaling pathway (Fig. 4).178 Multiple miRNAs and lncRNAs have been found to regulate PD-1 expression on the surface of tumor-infiltrating T cells and promote immunosuppression, thus promoting TIE (Table 5, Fig. 4).