Figure 4.

Estrogen-dependent formation of transformed cell foci by LEF-1-ER fusion products. CEF were infected with the constructs indicated on the left and then overlaid with nutrient agar containing estrogen (2 × 10⁻⁶ M), tamoxifen (1 × 10⁻⁷ M), or ethanol (vehicle). On day 20 after infection the cells were fixed and stained with crystal violet and photographed.