CD274 and head and neck squamous cell carcinoma: Interestingly, IFNγ, which restored of HLA class I expression and antigen presentation in tumor cells as discussed above is also a major inducer of PD-L1 expression as shown in multiple cancer types including HNSCC (Concha-Benavente et al., 2015), fibrosarcoma (Lee et al., 2005), glioblastoma (Han et al., 2009), and multiple myeloma cells (Liu et al., 2007).