β-catenin binds to the E1A-HD2 fusion protein in vitro. A. Diagram showing the viruses used in this study. Open circles represent four Tcf binding sites in the viral promoters. B. Co-precipitation of β-catenin through the HD2 domain. HT29 and SW480 cells were infected with the parental and E1A-HD2 viruses. E1A immunoprecipitates were immunoblotted for β-catenin, pRb and E1A. Asterisks indicate immunoglobulin light and heavy chains.