IRF4 and cancer: Interestingly, multiple genes encoding cell surface immune checkpoint receptors and their ligands were transcriptionally regulated by IRF4, including PD-L1 (CD274), PD1 (CD279), CTLA4 (CD152), B7-2 (CD86), LAG3 (CD223), and PD-L2 (CD273), in these virus-infected cancer cells (Figure 1A).