FOS and cancer: The results showed that the AP-1-containing enhancer element increased PD-L1 promoter-driven luciferase activity in an AP-1 dependent manner (Fig. 3C), and such luciferase activity was significantly increased after MLN4924 treatment for 24 h in both human cancer cell lines (H358, BxPC3) (Figs. 3D and S4C) and a murine colon cancer cell line CT26 (Fig. 3E).