Regulatory interplay between miR-21, JAG1 and 17beta-estradiol (E2) in breast cancer cells

► miR-21 directly targets and represses JAG1 levels in breast cancer cells. ► miR-21 targeting of JAG1 is affected by miR-21 levels. ► miR-21 and JAG1 expression levels are negatively correlated. ► 17beta-estradiol (E2) reduces mir-21 levels thereby increasing JAG1 levels. ► A novel regulatory interplay between miR-21, JAG1 and E2 in breast cancer cells.