The ovarian steroid hormone estrogen, as well as its receptor ER, are involved in this disease.460 In addition, other nuclear receptors, such as the NR4A protein family, may also participate in the progression of uterine fibroids.461 NR4A restricts the proliferation of primary leiomyoma smooth muscle cells by modeling the extracellular matrix, whereas low expression of NR4A contributes to the pathogenesis of uterine fibroids. The gene discussed is ESR1; the disease is uterine corpus leiomyoma.