Double-stranded RNA -mediated interference (RNAi ) is a new simple and fast research tool for shutting down genes and characterizes function of their respective proteins. Many strategies for design and delivery of siRNA to target cells are available. Here, we describe the use of lentiviral short hairpin RNA (shRNA) RNA silencing to identify the involvement of d-serine racemase (SR )- an enzyme that syntheses d-serine to modulate glutamate- N-methyl-D-aspartate receptor- in regulating rat cerebellar granule neurons (CGN ) apoptosis. Apoptosis is induced by serum and KCl withdrawal and is detected with fluorometric caspase 3 assay.