When leukocytes enter or exit the blood stream, they leave small wounds both in and between the vascular endothelial cells, which must be quickly repaired so that the endothelium can maintain its barrier function. Martinelli et al. reveal that wounding causes a loss of tension in endothelial cells, inducing the formation of ventral lamellipodia that close the holes left by transmigrating leukocytes. This biosights episode presents the paper by Martinelli et al. from the April 29, 2013, issue...