CD274 and infectious otitis media: In male mice, PD-L1-positive cells were barely detected in the control group of WT and Nrf2 KO mice, but AOM/DSS treatment significantly increased the frequencies of PD-L1-positive cells in both tumor (P = 0.020 for WT and P = 0.020 for Nrf2 KO; Figures 5A, E) and non-tumor areas (P = 0.024 for WT and P = 0.024 for Nrf2 KO; Figures 5A, C) in colon tissues.