Supported by Grants from the United States Public Health Service/National Institutes of Health, No. RO1CA135362,

Human T-cell leukemia virus type 1 (HTLV-1), the first human retrovirus discovered, is the etiological agent of adult-T-cell leukemia/lymphoma. The HTLV-1 encoded Tax protein is a potent oncoprotein that deregulates gene expression by constitutively activating nuclear factor-κB (NF-κB). Tax activation of NF-κB is critical for the immortalization and survival of HTLV-1-infected T cells. In this review, we summarize the present knowledge on mechanisms underlying Tax-mediated NF-κB activation, with an emphasis on post-translational modifications of Tax. © 2010 Baishideng. All rights reserved. Key words: Adult-T-cell leukemia/lymphoma; Human T-cell leukemia virus type 1; Nuclear factor-κB; Huma