Fig. 3. Endogenous reporter for β-catenin transcriptional activity reveals no changes in E-catenin^–/– mouse brains. (A) Schematic representation of TOPGAL reporter (DasGupta and Fuchs, 1999). The reporter contains three consensus Lef/Tcf-binding motifs (Lef) and a minimal c-fos promoter (P) to drive transcription of LacZ. (B-C') A similar pattern of β-catenin reporter expression in the telencephalon of wild-type (WT) and E-catenin^–/– (KO) embryos. Sagittal sections of brains from E12.5 (B,B') and E13.5 (C,C') embryos positive for TOPGAL transgene were stained for β-galactosidase (blue) and counterstained with nuclear Fast Red. HI, developing hippocampus. Scale bar in B: 0.19 mm for B,B' and 0.26 mm for C,C'. (D) Similar levels of β-catenin reporter expression were observed in wild-type (WT) and E-catenin^–/– (KO) mouse brains. Total protein lysates from E12.5 and E13.5 telencephalons fromTOPGAL-positive animals were analyzed by western blotting with anti-β-galactosidase (β-gal) and anti-β-actin antibodies. Con, control samples from TOPGAL-negative animals. The numbers indicate the relative amount of β-gal adjusted to the level of β-actin.