MLN8237 induces polyploidy in human T‐cell leukemia virus type 1 (HTLV‐1)‐uninfected T‐cell lines (a,b), but not in HTLV‐1‐infected T‐cell lines (c,d). Cells were exposed to 12.5 nm MLN8237 (MLN [+]) or vehicle (MLN [−]) for 24, 48, or 72 h. The cell cycle was analyzed by flow cytometry. Similar results were observed in triplicate experiments.