Exposure of esophageal cells to BA/A leads to activation of IKKα/β kinases and upregulation of the ΔNp73 protein.

<p><b>A.</b> Dynamics of IKKα/β phosphorylation in BA/A-treated cells. SK-GT-4 cells were treated with 100 µM BA cocktail, pH 4.0. Extracts were collected at the indicated time points and analyzed by Western blotting. Early (5–30 minutes) and late (4–24 hours) time points are shown. <b>B.</b> IKK kinase inhibitor Bay11–7085 downregulates the ΔNp73 protein. SK-GT-4 cells were pretreated with Bay11–7085 (10 µM) for 1 hour, treated with BA/A (100 µM) for 30 minutes and then incubated for an additional 7 hours in the presence of the indicated inhibitor. Total cell extracts were analyzed by Western blotting. <b>C.</b> Inhibition of IKK kinases by siRNA leads to downregulation of the ΔNp73 protein in BA/A-treated cells. SK-GT-4 cells were transfected with IKKα- or IKKβ- specific siRNA for 48 hours, treated with BA/A (100 µM) for 30 minutes, and then collected 7 hours after treatment. Levels of ΔNp73 were analyzed by Western blotting. <b>D.</b> Transfection of constitutively active IKKα and IKKβ mutants leads to upregulation of the ΔNp73 protein. SK-GT-4 cells were transfected with the indicated mutants for 24 hours and analyzed by Western blotting.