To examine whether the promoter of sGC subunits is methylated in breast cancer patients, we isolated genomic DNAs from normal and tumor portions of breast tissues from 10 breast cancer patients [5 patients carried ER+/Progesterone Receptor (PR)+ breast tumors, and the other 5 patients carried ER-/PR- breast tumors] (Fig 4). Here, ESR1 is linked to breast cancer.