At the request of the authors, the following manuscript has been retracted: “Spinal 5-HT3 Receptor Activation Induces Behavioral Hypersensitivity via a Neuronal-Glial-Neuronal Signaling Cascade” by Ming Gu, Kan Miyoshi, Ronald Dubner, Wei Guo, Shiping Zou, Ke Ren, Koichi Noguchi, and Feng Wei, which appeared on pages 12823–12836 of the September 7, 2011 issue.