Prinaberel (ERB 041) is a selective and potent estrogen receptor beta (ERbeta) agonist with anticancer activity that restores or increases ERbeta expression and reduces cancer cell proliferation in mouse squamous cell carcinoma and human carcinoma cells. Prinaberel exhibits anti-inflammatory activity, inhibits the NFkappaB pro-inflammatory signaling pathway, and induces apoptosis of ovarian cancer cells. study endometriosis.