The process of interaction between PD-1 and PD-L1/PD-L2 is mainly that PD-1 binds with PD-L1/PD-L2, transmits the co inhibitory signal of T cells antigen receptor and inhibits the production of various cytokines by suppressing the activation of T cells, thus assisting tumor immune escape. The gene discussed is CD274; the disease is neoplasm.