Serglycin is highly expressed by infiltrating immune cells in breast cancer(BC) tissues, while the mRNA and protein levels of SRGN were overexpressed in lung adenocarcinoma (LUAD) cell lines, in vivo accompanied by higher expression of PD-L1 in cancer cells and higher infiltration of PD-1+lymphocytes (20, 21). Here, PDCD1 is linked to breast cancer.