Fig. 2. The hypermethylated CAII promoter CpG island binds the MeCP2–corepressor complex in vivo. (A) Northern blot showing activation of CAII expression by treatment with the methylation inhibitor AZAdC (48 h, 500 nM) in HD3 cells. Band 4.1 serves as loading control. (B) Coupled co-immunoprecipitation–western blotting experiment with MeCP2 antibody showing association of the Sin3B–HDAC2 proteins with MeCP2, but not with preimmune serum. (C) ChIP experiment performed with indicated antibodies on chromatin from untreated HD3 cells and from cells treated for 48 h with AZAdC (500 nM). Recovered DNA was quantified using real-time PCR with control-, HS2- and promoter spanning primer sets. The background control region 7 kb upstream of the CAII promoter is used as control for which the PCR signal is arbitrarily set to 1 and signals were calculated compared to this.