S9.6 IP at Mammalian IgH switch regions requires RNase a pre-treatment of the harvested genomic nucleic acid. Immunoprecipitation with the S9.6 antibody was performed on stimulated or unstimulated wild type CH12F3.2a cells. The genomic DNA samples were pre-treated with RNase A before IP for Groups 4 through 6. Cytokine stimulation and RNase treatments are specified at the bottom. Half of the genomic DNA was pretreated with RNase H before IP. Background signals from mock samples with no antibody were subtracted. Values were normalized to the total input DNA to calculate the pull-down percentage. Three independent IP experiments were performed for each condition. Error bars represent standard error of the mean (SEM). The Sα region in Group 5 shows the highest level of S9.6 IP, though this level is only of borderline significance (p = 0.08) compared to the region at the same locus, but upstream of the EcoRI site. This reflects the limited signal to noise detection capability of S9.6.