ML-9 was originally identified as a selective Ca²⁺-calmodulin-dependent myosin light chain kinase inhibitor. Concentrations from 10-100 µM are effective at inhibiting vascular smooth muscle tension and reducing intracellular Ca²⁺concentrations.¹ML-9 also inhibits PKB/Akt activity with an IC₅₀range of 10-50 µM in rat primary adipocytes. This results in a specific inhibition of insulin-stimulated glucose transport and GLUT4/IGF II receptor translocation to the plasma membrane yet does not interfere with the antilipolytic effect of insulin.²Additionally, ML-9 inhibits other serine/threonine kinases including PKA (IC₅₀= ~20 µM), p90 S6 (IC₅₀= ~50 µM), and MAP kinase (IC₅₀= ~35 µM).²

1.Ito, S., Kume, H., Honjo, H., et al.ML-9, a myosin light chain kinase inhibitor, reduces intracellular Ca2+ concentration in guinea pig trachealisEuropean Journal of Pharmacology486325-333(2004) 2.Smith, U., Carvalho, E., Mosialou, E., et al.PKB inhibition prevents the stimulatory effect of insulin on glucose transport and protein translocation but not the antilipolytic effect in rat adipocytesBiochemical and Biophysical Research Communications268315-320(2000)