Correction

GENETICS. For the article “Quantitative mutant analysis of viral quasispecies by chip-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,” by Georgios Amexis, Paul Oeth, Kenneth Abel, Anna Ivshina, Francois Pelloquin, Charles R. Cantor, Andreas Brau, and Konstantin Chumakov, which appeared in number 21, October 9, 2001, of Proc. Natl. Acad. Sci. USA (98, 12097–12102; First Published October 2, 2001; 10.1073/pnas.211423298), the authors note the following. Due to a printer's error, “Andreas Brau” should be listed as “Andreas Braun.” The online version has been corrected.