Sphingomyelinase assay kit offers a homogenous method to measure the activity of sphingomyelinase in vitro. Sphingomyelinase catalyzes the cleavage of sphingomyelin, a component of most animal cells located on the outer leaflet of the cell membrane, into ceramide and phosphocholine. Activation of sphingomyelinase occurs by diverse stimuli leading to the induction of apoptosis (programmed cell death) through the generation of ceramide. The assay kit allows the user to quantify sphingomyelinase concentrations as low as 78 μU/mL in four hours using a standard microplate reader (absorbance at 595 nm).