CD4 and lung carcinoma: A recent study on the HKP1 (KrasG12Dp53−/−) immunocompetent, syngeneic mouse lung cancer model, which is histologically similar to human adenocarcinoma (27), used RNA-Seq analysis of fluorescence-activated cell sorting (FACS)-sorted tumor-infiltrating CD4+ and CD8+ T cells in order to reveal the intrinsic features of T cell behavior associated with early immune response to anti-PD-1 therapy (28).