Effects of imatinib and/or As₄S₄ on cell cycle distribution of K562 cells. (A) The cell cycle distribution analysis of K562 cells incubated with As₄S₄ and/or imatinib at different time points (n = 3, mean ± SD). CON indicates control; I 0.2, 0.2 μM imatinib; A2, 2 μM As₄S₄; and I 0.2A2, 0.2 μM imatinib and 2 μM As₄S₄. (B) Western blot analysis of some cell cycle–related proteins in K562 cells treated with imatinib and/or As₄S₄ for 48 hours.