Triparanol is a 24-dehydro cholesterol reductase (DHCR24) inhibitor (Ki = 0.523 µM), which is an enzyme involved in the biosynthesis of cholesterol. It has antitumor properties, such as decreasing proliferation and inducing apoptosis in many cancer cell lines and slowing tumor growth in a mouse xenograft model. It can also decrease Hedgehog pathway signaling in cancer cells. Formulations containing triparanol were discontinued in the 1960s due to serious adverse side effects, including rapid cataract development.