Figure 6.

The absence of Rb, E2F1, and p53 does not affect the apoptotic effects of β-catenin. (A) Full-length β-catenin–GFP was transfected into fibroblasts lacking each gene of interest (Rβ^−/−, E2F1^−/−, or p53^−/−). We also used fibroblasts immortalized with SV40 large T antigen wild-type (Tag WT), which blocks both Rb and p53 functions. As controls, we used Rβ-positive fibroblasts (Rb^+/+) and fibroblasts expressing SV40 Tag mutant (MT), which abolishes the blocking function on Rb. β-Catenin–GFP localizes in the nucleus in punctate patterns. Bar, 50 μm. (B) Overexpression of β-catenin induces apoptosis in all Rb-, E2F1-, and p53-deficient fibroblasts and in fibroblasts expressing SV40 Tag WT, ruling out the role of these genes in the apoptotic pathways of β-catenin.