ReadiPrep? Nuclear/Cytoplasmic Fractionation Kit. The ReadiPrep? Nuclear/Cytoplasmic Fractionation Kit offers stepwise isolation of nuclear and cytoplasmic extract from mammalian cells or tissue. The isolated proteins have high concentrations and preserve their biological activities. The nuclear and cytoplasmic extracts from ReadiPrep? Nuclear/Cytoplasmic Fractionation Kit are compatible with many downstream applications including enzyme activity assays and fluorescent Western blotting etc.