Fig. 2. ß-catenin accumulates in Apc^P-/- acinar cells. (A) Anti-pan ß-catenin immunofluorescence at E15.5, birth (P1), 1 month (confocal pictures are shown for this stage) and 12 months of age. In control mice (left column), ß-catenin staining is found in cell membranes at all stages analyzed. By contrast, in adult Apc^P-/- mice (right column) staining for ß-catenin is mainly nuclear in acinar cells from P1 (open arrows) but remains peripheral in most islet and ductal cells, as in controls. Notice that some islet cells display a cytoplasmic ß-catenin staining (small arrow) in old Apc^P-/- mice. (B) Western blot of total protein extracts from E15.5 and adult pancreata (50 µg per lane) using anti-unphosphorylated ß-catenin antibody and anti-ß-catenin-(phospho Y142) antibody. Unphosphorylated ß-catenin accumulates only in pancreatic extracts from Apc^P-/- adult mice and is always undetectable in isolated islets (right). ß-catenin-(phospho Y142) is abundant in adult acini, but undetectable in developing primordia or in isolated islets (1-month-old), whether control or Apc^P-/-. ß-tubulin and actin (lower row) show equal loading. d, duct; i, islet. Scale bars: 20 µm.