MMP9 and polycystic ovary syndrome: MF increases the expression of miR-29b-3p, a negative regulator of the MMP-2 and MMP-9 expression via decreasing the expression of histone H19 through methylation of the promoter in the gene encoding this histone, which leads to a decrease in the production of these enzymes and contributes to normalization of ovarian morphology in PCOS [300].