CHOLESTEROL is a sterol and lipid present in cell membranes, and is transported in the bloodstream of all animals. It is used to form cell membranes and hormones, and plays important roles in cell signaling processes. Cellular regulation of cholesterol levels is a complex system in which irregularities have been tied to obesity and heart disease. Increased cholesterol uptake has also been linked to highly proliferative cancer cells. Through monitoring cellular cholesterol uptake, one can explore these growing health problems and screen for possible drug treatments. This cholesterol uptake assay kit is based on cellular uptake of a fluorescently tagged cholesterol probe. The fluorescence intensity measured at lambda ex/em = 485/535 nm is proportional to the amount of cholesterol uptaken by the cells.