 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.Mitotic selection is a drug-free procedure for the selection of mitotic cells from a monolayer undergoing exponential growth.