Figure 7.

Proinflammatory S. typhimurium induces Ca²⁺-dependent phosphorylation of IκB-α. Immunoblots with anti–IκB-α or anti–phospho-IκB-α antibodies. (a) All model epithelia were pretreated with 50 μM MG-132 for 30 minutes. Whole cell extracts were prepared at the indicated times from cells treated with basolateral TNF-α or apical wild-type S. typhimurium (WT). Extracts were electrophoresed and immunoblotted with anti–IκB-α and anti–phospho-IκB-α antibodies. (b) Cells were pretreated with 50 μM MG-132 for 1 hour before addition of agonists as described in Figure 6b before immunoblot with antiphospho-IκB-α antisera. (c) Epithelia were treated with MG-132 and/or BAPTA as described in Methods, before activation with TNF-α (30 minutes) or Salmonella (1 hour). Extracts were immunoblotted with anti–IκB-α and anti–phospho-IκB-α antibodies as indicated.