OSC (Oxidosqualene Cyclase), also known as Lanosterol Synthase, is a key enzyme in the sterol biosynthesis pathway, responsible for catalyzing the synthesis of lanosterol, a crucial step in the production of cholesterol and other sterol compounds. OSC is primarily located in the endoplasmic reticulum, impacting cell membrane fluidity and the synthesis of various signaling molecules through its catalytic reaction. The specific expression of the OSC gene is essential for normal cellular function, with dysregulation or mutations associated with various diseases, including congenital cholesterol synthesis disorders and certain metabolic diseases.