(Upper) Estrogen-dependent agar colony formation by LEF-1-ER fusion products. CEF transfected with the indicated constructs were seeded in soft nutrient agar containing estrogen (2 × 10−6 M), tamoxifen (1 × 10−7 M), or ethanol (vehicle). Photographs of the agar colonies were taken on day 17 after infection. (Lower) Agar colony formation by various LEF-1 constructs. CEF transfected with RCAS (A), LEF-1 (B), LEF-1-VP16 (C), LEFΔN-VP16 (D), LEFΔN-βcat (E), and LEFΔN-βΔN (F) were seeded in soft nutrient agar. Photographed 17 days after infection.