BTO-1 (50 μM; 4 hours; U20S cells) results in monopolar spindles in a comparable fraction of mitotic cells. BTO-1(20 μM; 1 hour; PTK cells) shows a dose-dependent reduction in phospho-Cdc25C. BTO-1(25 μM; 1 hour; PTK cells) shows about 20 % reduction in H3 phosphorylation compared to control cells. BTO-1 in HeLa cells results in a blockage of Rho and Rho-GEF recruitment, which is essential for the assembly of a functional contractile ring[1][2].