RIPA Buffer continues to be a popular buffer to lyse plated and suspension cultured mammalian cells. The buffer extracts cytoplasmic, membrane, and nuclear proteins and is suitable for downstream assays such as reporter assays, protein assays, immunoassays and protein purification. 20 mL containing 125 mM Tris pH 7.6, 750 mM NaCl, 5% NP-40, 5% sodium deoxycholate, 0.5% SDS.