ESR1 and breast cancer: While most studies have indicated a potential beneficial effect of catalpol in breast cancer, Hao and colleagues showed that in T47D cells, a model of progesterone-specific luminal A subtype of breast cancer, catalpol (10−7 M or 10−6 M) up-regulated pS2 mRNA expression, increased ER-α protein expression and significantly enhanced the proliferation in T47D cells; this effect was attenuated by the anti-estrogenic agent ICI182 780 (10−8 M).