CD274 and lip and oral cavity carcinoma: The findings from this in vitro study, which demonstrated significant increases in PD-L1 expression as well as in cell invasion upon treatment with IFN-γ in the oral cancer cell lines, HN6 and HN15 (Figure 5I,J), are thus in line with those of a previous study [33] that emphasized the significant role of PD-L1 in cancer aggressiveness.