Furthermore, the frequencies of PD-L1-positive cells within tumor areas were strongly lower in Nrf2 KO female mice than in Nrf2 KO males (P = 0.025 for male vs female; Figures 5E, F), but not in WT mice, suggesting sex differences in PD-L1 expression in response to AOM/DSS treatment. This evidence concerns the gene NFE2L2 and infectious otitis media.