Suppression of HIAP-1 by lentiviral transduction of a shRNA expression cassette into HTLV-1–transformed cells. (A) Physical map of the shRNA lentiviral vector (pNL-SIN-CMV-BLR) and the inserted shRNA precursor specific for HIAP-1 and the nonsense precursor. (B) The HTLV-1–transformed T-cell lines (MT-2 and C91-PL) and HTLV-1–negative control cells (HuT-78) were infected with lentiviruses encoding shRNAs specific for HIAP-1 (siHIAP), nonsense shRNAs (sinon), empty lentiviruses (vector), and were mock-infected. The RNA of the cells was extracted, and subjected to RT-PCR using blasticidin S deaminase primers and β-actin primers as a control. (C) Quantitation of HIAP-1 expression by real-time RT-PCR. The HIAP-1 expression was normalized to the empty vector control. The bars represent the mean of 2 independent experiments and the mean error. (D) To detect RNAi-mediated reduction of HIAP-1 protein content, proteins were prepared from the transduced cells and analyzed by immunoblots. Specific bands were detected by HIAP-1– and β-actin–specific monoclonal antibodies.