Figure 2.

Stimulation of endogenous IKK activity by NIK and MEKK1. 293 cells were transiently transfected with either Xpress-tagged NIK or Xpress-tagged MEKK1 full-length expression vectors (1 μg DNA in A or 2 μg DNA in B/60-mm plate). After 24 hr, cells were treated or not with TNF (20 ng/ml for 10 min) and then lysed. Cell lysates were immunoprecipitated (IP) with either anti-IKKα or anti-IKKβ or anti-JNK antibodies. The IKK activity (KA) was determined by using glutathione S-transferase (GST)-IκBα (1–54) as a substrate. The JNK activity (KA) was determined by using GST-cJun (1–79) as a substrate.