Do you have any experience /data about efficiency of commonly used promoters: human CMV, mouse CMV, EF-1a, Ubc, CAG, PGK, H1, U6, in primary hepatocytes?
My understanding is that U6 works the best to drive RNAi to knockdown genes. I have used CMV, EF-1a, PGK promoters mentioned here but always in the context of cDNA expression. I have mostly used U6 for shRNA and I have, so far, no complaints. In any case, I am all ears to what makes U6 a better promoter for shRNA or is it truly the case.