Retraction.

B. González-Fernández , D.I. Sánchez , I. Crespo , B. San-Miguel , M. Álvarez , M.J. Tuñón , and J. González-Gallego , "Inhibition of the SphK1/S1P Signaling Pathway by Melatonin in Mice with Liver Fibrosis and Human Hepatic Stellate Cells," BioFactors 43, no. 2 (2016): 272-282, https://doi.org/10.1002/biof.1342. The above article, published online on 1 November 2016 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Irene Diaz-Moreno; International Union of Biochemistry and Molecular Biology (IUBMB); and Wiley Periodicals LLC. Following publication, concerns were raised by a third party that portions of Figures 1A, 2A, and 3A were duplicated. Internal investigation confirmed the duplications in these figures, as well as in Figure 4A. The authors provided some of the original data, but these were not sufficient to resolve the concerns, and the authors were unable to provide a satisfactory explanation. The retraction has been agreed because of concerns that the images were manipulated, affecting the interpretation of the data and results presented.