Is it possible to quantify protein content in RLT lysates?

It’s not possible to quantify protein content in RLT  lysates. One needs to do the acetone precipitation from Appendix F in the RNeasy Mini Handbook. Then, the pellet can be solubilized either in 5% SDS by boiling or by just adding 8 M Urea. 5% SDS is compatible with BCA. 8 M Urea has to be diluted to 3 M to be compatible with BCA.