Increased IKK activation in premalignant tal-1/scl thymocytes and tumors. Thymocytes isolated from 4-week-old tal-1/scl transgenic and control littermates were lysed and immunoprecipitated with an anti-IKK-γ antibody and used in an in vitro kinase assay with GST-IκBα as the substrate. Whole-cell lysates were also prepared from tal-1/scl tumor cell lines. To insure that equivalent amounts of IKK were immunoprecipitated, the lysates were probed with an anti-IKK-α antibody.