Protein levels were determined by western blot analysis as previously described.37 (link) Antibodies against β-catenin (#8480), CD44 (#5640), and p-CRKL (#3181) were purchased from Cell Signaling Technology (Danvers, MA), and survivin (AF886) from R&D Systems (Minneapolis, MN). β-actin was used as a loading control. Proteins were visualized with Odyssey infrared imaging system and quantitated using the Odyssey software program (version 3.0; LI-COR Biotechnology, Lincoln, Nebraska).