Pierce NE-PER final insoluble pellet, is it chromatin and how to solubilize it? - (Apr/26/2015 )

I have been using the Pierce NE-PER kit to isolate cytoplasmic and nuclear fractions from human epithelial cell lines for Western blotting. I would also like to recover the chromatin fraction. I was wondering what the remaining soluble pellet consists of after the nuclear soluble fraction is recovered? Is this chromatin and other cellular debris? Is there a way to isolate the chromatin from the pellet? Sonication or nuclease treatment? Will this solubilize these DNA associated proteins then allow you to pellet the other debris to separate the fraction? Or should I just add something to this pellet to solubilize and using this for Western blot such as Laemmli sample buffer? Are you estimating this protein fraction or just running a set volume for Western blot? If there is a better protocol for cyto, nuc, chromatin fractionation, can you please recommend one. 

Thanks!

I talked with Thermo (Pierce). After removing the soluble nuclear extract, the remaining insoluble pellet contains chromatin, cytoskeletal proteins and cellular debris. To recover the chromatin associated proteins, add nuclear extraction buffer containing micrococcal nuclease + CaCl2, briefly vortex and incubate. Finally, spin this down to pellet and remove the soluble portion containing chromatin associated proteins.