Hi Ammar

I think it is correct, you surely can use proteinase K as a lysis agent, and in the case of adherent cells, you can combine the proteinase k treatment with a hypotonic buffer with EDTA (which will helps on detachment)...Maybe Tris 10 mM pH 8.0 with 1 mM EDTA should be a good lysis buffer for the treatment with proteinase K... Surely you will have the cell lysis, with the advantage of being in the absence of detergents with could influence on the DNA preservation..

Thanks for the answer. Just to get my question exact, I am planning to work on adherent cells (in situ cDNA synthesis) that were previously lysed by only using protinase K with a commercial buffer containing 20 mM Tris-acetate, 10 mM Magnesium acetate, 10 mM Magnesium acetate, 50 mM Potassium acetate, 50 mM Potassium acetate, 1 mM DTT 100 µg/ml BSA. I am planning to capture both cDNA and RNA on beads. Will the proteinase K with the mentioned buffer (without detergent) be sufficient to expose the cDNA and RNA for the bead capture? or I need the lysis buffere o get buffer to get rid of the remaining cell membrane components?

I would always recommend a detergent. Even if you pick a really hypotonic buffer (so all your cells pop), you may still get key cell content trapped within the burst membrane 'ghosts'. A detergent will loosen/dissolve membranes and liberate all your cell content more evenly. There are a host of mild detergents to pick from (though triton X-100 remains ever-popular, mostly because: cheap), and most of them have no significant effect on cDNA synthesis or oligo:oligo hybridisation.