Nature 415, 92–96 (2002).

In this Letter, the commercial polyclonal antiserum used to detect endogenous XBP-1 was sc-7160 (Santa Cruz Biotechnology) and not sc-8015, as erroneously stated. The antibody sc-8015 is a mouse monoclonal and, in our hands, is not useful in detecting the endogenous protein by immunoblotting.