Studies exploring the impact of culturing immortalized fibroid and myometrial cells with TGF-β3 found increased mRNA and protein production of ECM proteins collagen 1A1 [29, 42], fibronectin 1 [29, 42] and connective tissue growth factor [29] in both cell types, with increased expression in treated myometrial cells to nearly the levels found in leiomyoma cells [29]. This evidence concerns the gene TGFB3 and leiomyoma.