Hi, I have a problem in poly(A)-Northern: A possible signal is much longer (4.5-4.7 kb) than my mouse cDNA (1.8 kb). How do I discriminate the real signal and 28S rRNA which might be present in poly(A)RNA and even recognized by my probe? With rRNA specific probe? Does anybody know where I can find a probe for mouse 28S rRNA? best regards, Pasi Nokelainen