I've been using trizol to homogenize frozen nerves. I've pooled 2, 4, and 6 nerves and ran qPCR for GAPDH. The Ct values for all combinations were about the same (~23). So I used 2 nerves to run a data set, but this time my Ct values for GAPDH ranged from 26 to 31. I think I may just not have any RNA, and the readout of the RNA concentrations is something else. What protocols have worked for others?