Kinetics of IκBα_32/36A inducibility after doxycycline treatment. Cells were (+) or were not (−) treated with doxycycline at 2 μg/mL. Times of protein extraction are indicated at the top of the figure (D0: protein extraction was performed immediately after doxycycline treatment; D1, D2, D4, and D7: protein extraction was performed immediately after 1, 2, 4, and 7 days of doxycycline treatment, respectively). Upper panel: Western blot detection of IκBα after SDS–PAGE with stacking gel; mutated and endogenous IκBα are indicated by the arrow. Lower panel: NF-κB-binding activity assessed by EMSA.