Simvastatin is semi-synthetic, slightly more hydrophobic analogue of lovastatin. Like lovastatin, simvastatin is a specific inhibitor of HMG-CoA reductase and is used therapeutically to reduce LDL cholesterol. More recently, the statins have become important biochemical probes in cell biology. Their involvement in many events can be correlated to their primary mode of action, however, the mechanism of action of many other effects is less apparent.