Figure 3.

Activation of the Topflash reporter by LEF-1-fusion constructs. (A) Human 293 cells were transfected with the Topflash reporter plasmid and expression plasmids for LEF-1, LEF-1-ER, or LEFΔN-ER. Cells were treated with 10⁻⁶ M 17β-estradiol (+17βE2) in ethanol or solvent only (−17βE2) for 24 hr. Luciferase activities were determined as described in Materials and Methods and are expressed as relative activity. Reporter gene activity in control cells transfected with Topflash and empty expression vector were arbitrarily set as 1. Values given are derived from at least three independent experiments. (B) Human 293 cells were transfected with the Topflash reporter plasmid and expression plasmids for LEF-1, LEF-1-VP16, or LEFΔN-VP16 as indicated. Luciferase activities were determined as in A. (C) Mouse Neuro2a cells were transfected with the Topflash reporter plasmid and expression plasmids for LEFΔN, LEFΔN-βcat, LEFΔN-βΔN, and wild-type (WT) or mutant β-catenin as indicated. Luciferase activities were determined as in A. Note the different scales in A, B, and C.