8E4 recognizes all deleted forms of B-catenin. (A) Schematic overview of the β-catenin molecule, with emphasis on the N-terminus. The 4 well-characterized Ser and Thr amino acids that are regulated by phosphorylation are shown as well as the various deletion constructs used to express myc-tagged truncated forms of β-catenin. (B) The 293 cells were transfected with myc-tagged β-catenin deletion constructs to identify the epitope recognized by 8E7 and 8E4. The endogenous β-catenin band is indicated by a black arrow, the open arrow indicates the transfected, N-terminal deleted form. Similar to the pan–β-catenin antibody (TL), 8E4 recognizes all deletion constructs, whereas 8E7 (αABC) only recognizes deleted β-catenin forms up to Δ35. The following antibodies were used: αABC/8E7 (Upstate Biotech, Lake Placid, NY; catalog no. 05-665), 8E4 (Upstate Biotech; catalog no. 05-601), TL (BD Transduction Laboratories, San Jose, CA; anti–β-catenin; catalog no. 610154), α-Myc (clone 9E10; supernatant of hybridoma used).