IKK protein level and kinase activity are not affected by As/IFN in HTLV-1⁺ cells. (A) Effects of As, IFN, and combined As/IFN on IKK-α, IKK-β, and IKK-γ protein levels in HuT-102 cells after 48 hours of exposure to these drugs. Equal protein loading was assessed by hybridization with anti-GAPDH antibodies. (B) Effect of As, IFN, and combined As/IFN on IKK activity in HTLV-1⁺ cells. Equal amounts of lysates from HuT-102, Jurkat, and C-8166 cells were immunoprecipitated with anti–IKK-α antibody. Kinase activity (KA) was determined as described in “Materials and methods” using (GST)-IκB-α as substrate. The membranes were subsequently probed with anti–IKK-α antibody to determine the amounts of immunoprecipitated kinases (IKK). Negative control reactions were performed without anti–IKK-α antibody (–Ab) or without (GST)-IκB-α (–substrate).