KRAS and lung carcinoma: Notably, in the studies that have investigated the intrinsic role of PD-L1 in lung cancer the cells utilized were mesenchymal lung cancer cell lines which harbored KRAS and/or p53 mutations, suggesting that the tumor cells metastatic capacity and mutational status may not be determining factors as to whether PD-L1 exhibits a pro-tumor or anti-tumor role in lung cancer.