In vitro activity: BMS-5, also known as LIMKI-3, is an analog of BMS-3 and potent inhibitor of the LIM kinase (LIMK) with IC50 values of 7 and 8 nM for LIMK1 and LIMK2 respectively. BMS-5 inhibits cofilin-Ser3 phosphorylation in a dose-dependent manner in Nf2ΔEx2 mouse Schwann cells (MSCs) with an IC50 of ~2 μM. Inhibition of LIMK1 by specific inhibitors (BMS-5) resulted in lower levels of actin polymerization during capacitation and a dramatic decrease in the percentage of sperm that undergo acrosomal exocytosis. Thus, we demonstrated for the first time that the master regulators of actin dynamics in somatic cells are present and active in mouse sperm. Combining the results of our present study with other results from the literature, we have proposed a working model regarding how LIMK1 and Cofilin control acrosomal exocytosis in mouse sperm.

Kinase Assay: BMS-5 reduces Nf2ΔEx2 MSC viability in a dose-dependent manner with an IC50 of 3.9 μM, but does not significantly reduce the viability of control Nf2flox2/flox2 MSCs at equivalent BMS-5 concentrations. At 10 μM BMS-5, Nf2ΔEx2 MSC viability is 40% compared to 83% for controls

Cell Assay: BMS-5 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.