Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): Sox17 and Sox4 have opposite effects on Wnt activity and proliferation of SW480 colon carcinoma cells. Small interfering RNA (siRNA)-mediated knockdown of SOX17 and SOX4 proteins in SW480 cells is shown. SW480 cells were transfected with 50 nM of a scrambled control siRNA or the sox siRNA. Confocal images of transfected SW480 cells show the typical perinuclear localization of the fluorescently labeled control siRNA (red). Nuclei are stained with the green nuclear Sytox Green. (See related article on p. 7802.)