IκB-ϵ degradation by the proteasome is blocked by As exposure in HTLV-1⁺ cells. Effects of As, IFN, As/IFN combination, or MG132 on IκB-ϵ protein levels in HuT-102 cells after 48 hours of exposure to these drugs. Equal protein loading was assessed by hybridization with antiactin or anti-GAPDH antibodies.