BMS-3 is a potent LIMK inhibitor with IC₅₀s of 5 nM and 6 nM for LIMK1 and LIMK2, respectively. IC50 & Target: IC50: 5 nM (LIMK1), 6 nM (LIMK2)^[1] In Vitro: BMS-3 (Compound 2) causes a dose-dependent reduction in cell count and induces mitotic arrest by increases in total nuclear DNA intensity and histone H3 phosphorylation after 24 h treatment in A549 human lung cancer cells. BMS-3 inhibits A549 human lung cancer cells with EC₅₀ value of 154 nM^[1]. BMS-3 is used to demonstrate the direct participation of LIMK1 in the phosphorylation of Cofilin. Inhibition of p-LIMK with 1-50 μM of BMS-3 results in a dose-dependent decrease of p-Cofilin after 10 min incubation in capacitating conditions. As a control, sperm are also incubated for 10 min under non-capacitating conditions which result in low levels of p-Cofilin. In the presence of 1 or 50 μM of BMS-3, actin polymerization levels are significantly lower compared to controls (DMSO). Mouse sperm are incubated under capacitating conditions for 90 min in the presence or absence of increasing concentrations of p-LIMK inhibitor BMS-3 (0, 1, 10 and 50 μM). The increasing concentrations of BMS-3 result in a strong decrease on the percentage of sperm that undergoes acrosomal exocytosis after stimulation with 20 μM of Progesterone^[2].