CD274 and cancer: We first used RT-qPCR to analyze the levels in PB cells of mRNAs encoding the immune checkpoint genes (ICGs) PDCD/CD274 (Iwai et al., 2017) in view of the cancer resistance of Klf1(K74R) mice (Figure 4) as well as increased levels of PDCD and CD274 in aged or tumorigenic mice (Jiang et al., 2019).