This FractionPREP™ Cell Fractionation system is designed to provide reproducible extraction of four subcellular protein fractions (Cytosol, nucleus, membrane/particulate, and cytoskeletal fractions) from a single mammalian sample. The method is fast and simple, needing only 2 hours and no ultracentrifugation involved. All four protein fractions obtained are suitable for many downstream applications such as 1-D or 2-D gel, enzyme activity assays, gel shift assay, and Western blotting.