IRS1 is also reported to be involved in the upregulation of collagen genes, including COL4A1, COL4A2 and COL6A3, suggesting that IRS1 possibly contributes to the leiomyoma nodule formation by upregulating the gene expression of COL4A1, COL4A2, and COL6A3 [47]. This evidence concerns the gene COL4A1 and leiomyoma.