PGR and breast cancer: Cui and colleagues used 3′UTR luciferase reporter assays and western blotting to confirm miR-126-3p regulation of PGR expression as well as proliferation and β-casein expression of mouse mammary epithelial cells [58], while miR-129-2 was reported to down-regulate PGR expression in response to progesterone treatment in breast cancer cell lines [59].