KITLG and chronic obstructive pulmonary disease: In addition to Keap1, Nrf2 can be subjected to SCF/β‐TrCP‐dependent ubiquitination and proteasomal degradation in a GSK3β‐dependent but β‐catenin‐independent manner.10, 22 GSK‐3β is one of the β‐catenin destruction complexes in Wnt pathway as the previously described.5, 23 Although Wnt/β‐catenin pathway has been shown to protect against the development of COPD/emphysema,5, 24 it remains unknown whether these protective effects are mediated by Nrf2.