Figure 6.

Expression of ER and PR in fibroid xenografts and its correlation with proliferation. Fibroid xenografts were treated with estradiol (E₂) plus progesterone (P₄) for 2 wk. DAPI (blue), Ki67 (red), and ERα (upper panels) or PR (lower panels) immunofluorescent staining was done. Ki67-positive cells (arrows) are also positive for ERα and PR. E₂ induces expression of PR, and P₄ action via PR increases the size of fibroid through accumulation of ECM, proliferation, and hypertrophy of fibroid cells. [Modified from H. Ishikawa et al.: Progesterone is essential for maintenance and growth of uterine leiomyoma. Endocrinology 151:2433–2442, 2010 (7), with permission. © The Endocrine Society.]