Foster WM, Adler KB, Crews AL, Potts EN, Fischer BM, Voynow JA. MARCKS-related peptide modulates in vivo the secretion of airway Muc5ac. Am J Physiol Lung Cell Mol Physiol 299: L345–L352; doi: 10.1152/ajplung.00067.2010. The authors have discovered that Figs. 1, 2, and 6 are not reliable. We offer our sincere apologies for the errors and for any inconvenience associated with the publication of the article. The paper is therefore being retracted by the American Physiological Society at the request of Dr. Voynow, and with the approval of the coauthors.