Following this study with the FD1 peptide in which we tested the proposed ferroxidase activity of amyloid precursor protein (APP), we have published a paper ( Honarmand Ebrahimi K, et al. (2013) The Amyloid Precursor Protein (APP) Does Not Have a Ferroxidase Site in Its E2 Domain, PLoS ONE 8(8): e72177). In this new study we tested the ferroxidase activity of the E2 domain of APP. Consistent with our data on the FD1 peptide, our new study shows that the E2 domain of APP does not have ferroxidase activity and APP possibly does not act as a ferroxidase.