Antibodies to APP were monoclonal anti-APP 22C11 (Chemicon), monoclonal anti-APP369 (gift of Dr. Sam Gandy), monoclonal anti-APPC7 (gift of Dr. Dennis Selkoe), monoclonal 4G8 (Endogen), and monoclonal anti-APP6E10 (Signet). Polyclonal anti-BACE and anti-nicastrin (Affinity BioReagents); Anti-calreticulin, anti-GM130 and anti-EEA were from StressGen Biotechnologies Corp or Transduction Laboratories. Monoclonal anti-CTF-PS1 (MSXPS1) (Chemicon) and monoclonal anti-TNF-alpha (Fitzgerald Industries International) were also used in this study.