A,B. COS-1 cells were transiently transfected with wt ERα, truncated ERα mutants HE15 and HEG19, an ERE-CAT reporter or GR and an MMTV-CAT reporter andβ-gal and treated for 24 hours with estradiol (1nM), EGF (150ng/ml), and calcium (1mM) in the presence and absence of the antiestrogen ICI-182,780 (500 nM) and the PLC inhibitor U73122 (2μM). The amount of CAT activity was measured and normalized to the amount of β-galactosidase activity. The results are expressed as percent control (mean±SD; three independent experiments). *, p < 0.05; **; p < 0.005; ***, p < 0.0005. a, compared to control; b, compared to treatment.
C. Schematic representation of ERα mutants.