The level of arsenite sensitivity of HTLV-1–infected T cells correlates with the level of SG-forming activity. (A,B) HTLV-1–uninfected (Jurkat and MOLT-4) and HTLV-1–infected (SLB-1 and MT-4) T cells were treated with 0.5 mM of sodium arsenite for 30 minutes and then were stained with anti-USP10 antibodies (green), anti-Tax antibodies (red), and Hoechst33258 (blue). The arrows indicate cells with colocalization of USP10 and Tax. The bar indicates 10 μm in (A). The SG (%) in the indicated cells is presented in (B). (C) HTLV-1–uninfected (Jurkat and MOLT-4) and HTLV-1–infected (MT-4 and SLB-1) T cells were treated with 5 μM of sodium arsenite for 48 hours and then were stained with PI. The proportion of the sub-G1 population (apoptotic cells) was measured using flow cytometry. (D) Jurkat and SLB-1 cells were incubated with or without 10 mM of NAC, further treated with 5 μM of sodium arsenite for 48 hours, and stained with PI. The proportion of sub-G1 populations (%) was measured using flow cytometry. In all experiments, the values denote mean ± SD; ***P < .001.