Nuclear staining associated with mAb 8E7 is observed in β-catenin null cells. A&B: Mouse L cell fibroblasts +/- Wnt3a A. Immunofluorescence staining of total (TL-) β-catenin (mAb clone 14, BD Biosciences) and ABC in mouse L cells stably expressing Wnt3a (right) or an empty vector (left). Note prominent nuclear staining in both Wnt3a expressing and non-expressing cells using 8E7 mAb. Exposure times for TL-β-catenin and ABC images are 1313 and 1439 milliseconds, respectively.B. Corresponding immuno-blot. Note that 8E7 detects non-specific band at ~160 kDa (*). C&D: WT and β-catenin/plakoglobin null F9 teratocarcinoma cells immunostained with antibodies that recognize TL- and ABC. C. The split panel (upper right) shows the presence of β-catenin/plakoglobin null F9 cells on the coverslip (phase) that are not stained with the TL-β-catenin antibody, but show a diffuse cytoplasmic/nuclear stain with mAb 8E7 (lower right). Inset shows the GAM secondary antibody control. Exposure times for TL-β-catenin and ABC images are 228 and 453 milliseconds, respectively. D. Corresponding immunoblot shows that 8E7 detects a non-specific band at ~160 kDa in F9 cells (*). It is unclear whether this non-specific band contributes to background nuclear staining.