A single commonly- used chemical method exists for synchronization of cells in G1. It involves [[Lovastatin]], a reversible competitive inhibitor of [[HMG-CoA reductase|3-hydroxy-3-methylglutaryl-coenzyme A reductase]], an enzyme vital in the production of [[mevalonic acid]]. Mevalonic acid is a key intermediate in the [[mevalonate pathway]] responsible for synthesis of [[cholesterol]]. Addition of cholesterol to Lovastatin-treated cells does not undo the arrest affect, so Lovastatin appears to inhibit the formation of some early intermediate in the pathway that is essential for progression through early G1.<ref>{{Cite journal|last1=Keyomarsi|first1=Khandan|last2=Sandoval|first2=Larue|last3=Band|first3=Vilma|last4=Pardee|first4=Arthur B.|date=1 July 1991|title=Synchronization of Tumor and Normal Cells from G1 to Multiple Cell Cycles by Lovastatin|journal=Cancer Research|volume=51|issue=13|pages=3602–3609|pmid=1711413}}</ref>
