To determine whether ATRA impacted the TGF-β pathway regulation of specific genes, we examined the expression of matrix metalloproteinase-2 (MMP-2) which is regulated by TGF-β in leiomyomas.32,33 As shown in Table 1, untreated leiomyoma cells demonstrated a 6·65 ± 1·22-fold elevation of MMP-2 gene. Here, TGFB1 is linked to leiomyoma.