PDCD1 and cancer: Next, we co-cultured A375, MDA-MB-231 and SK-OV-3 cells, respectively, with PD-1 expressed activated Jurkat E6 T cell to imitate the tumor cell killing effect by T cells when PD-1 and PD-L1 interacted (Supplementary Fig. S8), and then examined the cancer cell proliferation after exposure to CGA and IFN-γ.