Antibodies used were:Rabbit polyclonal antiserum R222 against PS1/NTF and mouse monoclonal antibody 33B10 specific for PS1/CTF were prepared as described (Georgakopoulos et al., 1999). Anti-N-cadherin (C32) and anti-E-cadherin (C36) antibodies were from BD Transduction Laboratories. Anti-ß-tubulin, anti-CBP (A-22), anti-c-Fos, and anti-ubiquitin (P4D1) were from Santa Cruz Biotechnology. Antibody against phosphorylated CREB at Ser133 (1B6) were from Cell Signaling Technology. Anti-Histone H3 antibody was from Upstate Biotechnology.