NFE2L2 and Hyperkeratosis: Although Pparγ is a direct transcriptional target of Nrf2[36], Pparβ/δ is more likely to be the isoform involved among the three Ppar isoforms because Pparβ/δ agonists were known to cause terminal differentiation of keratinocytes in vitro[25], [37] and dermal hyperkeratosis in vivo[38].