CHI3L1, derived from M2 macrophages, induces gallbladder cancer cells to secrete GDF15 and promotes programmed cell death protein 1 (PD-1) expression via P13K/AKT signaling to inhibit the cytotoxic effect of T cells, leading to the immune escape of tumor cells [161]. The gene discussed is CHI3L1; the disease is gallbladder cancer.