Understanding the molecular mechanism of drug action would then benefit from elucidating the central role of myosin isoform dependence in OM effects, as explored in the human heart, which shows a sharp difference in myosin isoform expression in young and healthy subjects, with the atria predominantly expressing α-fast MyH-6 and the ventricles expressing almost 100% β-slow MyH-7. The gene discussed is MYH14; the disease is ocular melanoma.