Corachán A, Trejo MG, Carbajo-García MC, et al. - Via this prospective study, researchers examined if vitamin D (VitD) impedes cell proliferation and Wnt/β-catenin and transforming growth factor−β (TGFβ) signaling pathways in uterine leiomyomas independent of mediator complex subunit 12 ( MED12) mutation status. Uterine leiomyoma and myometrium samples were collected from women with uterine leiomyoma without any treatment (n = 37) undergoing surgery because of symptomatic leiomyoma pathology. Wnt/β-catenin and TGFβ pathways and proliferation were analyzed in leiomyoma and myometrial tissue as well as in VitD-treated human uterine leiomyoma primary (HULP) cells analyzed by Sanger sequencing. Sequencing data indicated presence of MED12 mutation in 46% of leiomyomas. MED12-mutated leiomyomas had significantly increased expression of Wnt/β-catenin and TGFβ pathway genes compared with matched myometrium; there were no significant differences in wild-type (WT) leiomyomas. Observations suggest that VitD impeded Wnt/β-catenin and TGFβ pathways in HULP cells despite molecular disparities between MED12-mutated and WT leiomyomas, indicating VitD as an effective treatment to decrease proliferation and extracellular matrix formation in different molecular subtypes of uterine leiomyomas.