On the cover: Pseudocolor rendering of an image of the cytoskeleton of a cultured mouse podocyte. High pixel values are assigned white/yellow colors, representing higher density of actin molecules, and in contrast, low pixel values are assigned purple/blue colors, representing areas of lower density of actin molecules. Anna Greka, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts and Broad Institute of MIT and Harvard, Cambridge, Massachusetts