The authors wish to retract the article titled "Critical Role of Notch Signaling in Osteosarcoma Invasion and Metastasis," which was published in the May 15, 2008, issue of Clinical Cancer Research (1). Many years after this article was published, we obtained new information showing that two of the cell lines used in this publication, OS 187 and COL, are not osteosarcoma cell lines. Both lines ...