Figure1 . Ligation of PD-1 to PD-L1 leads to the inhibition of C3G, LAT, and PI3K pathways. Subsequently, IL-2 emission is blocked. Also, the proliferation and adhesion of T cells decrease. This attachment also leads to overexpression of IL-10 and the resultant decrease of T cells reproduction. As a result, T cell activity, cytokine release, and cytotoxicity of T cells decrease.