To unravel such mutations, we implanted the MC38 murine colorectal cancer (CRC) cell line to C57BL/6 mice (wildtype, WT), and treated them with monoclonal antibodies against mouse programmed death protein 1 (PD-1) or programmed cell death ligand protein 1 (PD-L1). Here, PDCD1 is linked to colorectal cancer.