Designed to provide reproducible extraction of four subcellular protein fractions (cytosol, nucleus, membrane/particulate, and cytoskeletal fractions) from a single mammalian sample; the percentage of proteins in the different fractions are cell-dependent, usually in the range of approx.20-30% cytosol, approx.25-35% membrane (organelles), approx.15-25% Nuclei, approx.15-25% insoluble