S-phase arrest and Cyclin E stabilization in RhoBTB3-depleted cells. (A) Flow cytometry of control or RhoBTB3-siRNA–treated cells at 24, 48, and 72 h after transfection. Propidium iodide staining was used to determine DNA content. A representative example from one of three independent experiments is shown. (B) Anti–α-tubulin staining of control and RhoBTB3-siRNA–treated cells. Arrowheads in inset indicate mitotic cells. Bar, 40 µm (inset, 10 µm). (C) Immunoblot detection of protein levels after 72 h with control or RhoBTB3-siRNA; molecular mass marker mobility is shown at left in kilodaltons. (D) Quantitation of protein levels from blots as in C. t test ;*, P < 0.05; **, P < 0.01; error bars represent SEM; n ≥ 3.