Editorial Expression of Concern for multiple articles

Correction for “Genetic inactivation of AKT1, AKT2, and PDPK1 in human colorectal cancer cells clarifies their roles in tumor growth regulation,” by Kajsa Ericson, Christine Gan, Ian Cheong, Carlo Rago, Yardena Samuels, Victor E. Velculescu, Kenneth W. Kinzler, David L. Huso, Bert Vogelstein, and Nickolas Papadopoulos, which appeared in issue 6, February 9, 2010, of Proc Natl Acad Sci USA (107:2598–2603; first published January 20, 2010; 10.1073/pnas.0914018107). The authors note that all columns and error bars in their figures represent means and SDs.