Analysis of methylation and product expression of the ER gene in nude mice. A shows that the tumor of control mice (CTR lanes) was methylated as shown by the band in the Lane H indicating no digestion with HpaII. The band disappeared with the treatment with 5-aza-CdR and hydralazine, which indicates gene demethylation. In PROC (procainamide) lanes, the band is absent in MspI but is very weak in HpaII, indicating that was only partially demethylated; B and D are the product expression by RT-PCR and Western blot. In both cases, the intensity of bands in procainamide is weaker, correlating with a partial demethylation, (C and E are the loading controls, GAPDH and actine respectively). G is undigested genomic DNA. (Reproduced with permission from the AACR. Ref. 83. Clin Cancer Res 2003, 9:1596–1603).