CD8A and non-small cell lung carcinoma: For instance, the MEK inhibitor selumetinib increases PD-1 expression on CD8+ T cells in KRAS-mutant NSCLC (59), while dual inhibition of MEK and PD-1/PD-L1 elevates tumor-infiltrating CD8+ and CD4+ T cells in KRAS/p53-driven lung cancer models (60).