Ca2+ and mitochondrial ROS: Both hero and villain in membrane repair.

Membrane repair is a symphony of signaling, conducted principally by the steep influx of Ca2+ through an injured membrane. In this issue of Science Signaling, Horn et al reveal unique interplay between Ca2+ influx and mitochondrially generated reactive oxygen species (mtROS) to enhance actin-mediated wound closure for survival of injured mammalian muscle and nonmuscle cells.