FIG. 7.

β-Catenin activates transcription in two steps. (A) The activity of a pTOPFLASH was determined by transfecting 293 cells with expression vectors encoding LEF1, β-catenin, and β-cateninΔCT in the indicated combinations. (B) 293 cells were transfected with the indicated expression constructs. Proteins complexed to β-cateninΔCT were identified by immunoprecipitation using a monoclonal antibody that recognizes the Glu-Glu epitope on the plasmid-expressed β-catenin protein. Associated LEF1 or HDAC1 was detected by probing Western blots for their FLAG epitopes. In each cell extract, FLAG-LEF1 was expressed to similar levels (data not shown). A and R mark the lanes showing experiments performed under activation and repression conditions, respectively.