The editors hereby retract the article titled “Antisense Knockdown of Sphingosine Kinase 1 in Human Macrophages Inhibits C5a Receptor-Dependent Signal Transduction, Ca2+ Signals, Enzyme Release, Cytokine Production, and Chemotaxis” by Alirio J. Melendez and Farazeela Bte Mohd Ibrahim, The Journal of Immunology, 2004, 173: 1596–1603.

An investigation by the National University of Singapore concluded that Fig. 2A and 2C display irregular backgrounds that suggest the bands were improperly inserted. The investigation also concluded that Fig. 2A was duplicated in Zhi et al., Journal of Cellular Physiology, 2006, 208: 109–115, which has been retracted by Dr. Gary S. Stein, the Editor-in-Chief of that journal.

The Investigative Committee of the National University of Singapore concluded that Dr. Melendez committed serious scientific misconduct. The committee found no evidence indicating that other coauthors were involved in the scientific misconduct.