This study investigated gene expression programs that regulate the proliferation and differentiation of myometrial and <i>MED12</i>-mutant leiomyoma stem cells during long-term organ culture.<h4>Results</h4>Comparison of normal and tumor tissues at baseline and after culture revealed several fibroid transcriptional signatures that were preserved during prolonged <i>ex vivo</i> culture. This evidence concerns the gene MED12 and neoplasm.