Further confirming that CDDO-Me induced Nrf2 pathway activation in a Nrf2-dependent manner, N2a cells that had been pretreated with the Nrf2 inhibitor ATRA before CDDO-Me treatment and SC16 infection showed significantly decreased Nrf2, HO-1 and NQO1 expression (P < 0.01). This evidence concerns the gene NFE2L2 and infection.