It was demonstrated that exogenous miR-423-5p is capable of inhibiting PGR gene transcription in vitro [77], miR-126-3p suppresses PgR expression in mouse mammary gland [78], and miR-181a, miR-23a, and miR-26b down-regulate PgR in ERα(+) BC [79,80]. This evidence concerns the gene PGR and breast cancer.