Fig. 1
From: Tumor immunotherapies by immune checkpoint inhibitors (ICIs); the pros and cons
The inhibitory effects of the CTLA-4/B7 on T cell anti-tumor activities. CTLA-4 is expressed on activated T cells, is about 30% homologous with CD28 and binds to the same ligands as CD28, known as B7-1 and B7-2 expressed on APCs or tumor cells. This interaction results in activation of SHP2 and so down-regulation of PI3K/AKT axis. Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), SH2 containing protein tyrosine phosphatase-2 (SHP2), Phosphoinositide 3-kinases (PI3Ks), Phosphatidylinositol-4,5-bisphosphate (PIP2), Phosphatidylinositol (3,4,5)-trisphosphate (PIP3), Lymphocyte-specific protein tyrosine kinase (LCK), T cell receptor (TCR), Nuclear factor-κB (NF-κB), Mammalian target of rapamycin (mTOR), B-cell lymphoma-extra large (Bcl-xL), Major histocompatibility complex class II (MHCII), Interleukin-2 (IL-2)