Why do some animals regenerate lost tissues after injury while others don’t? Researchers from the lab of Kerstin Bartscherer (Osnabrück University and formerly Hubrecht Institute) and Ashley Seifert (University of Kentucky) studied spiny mice, which have a remarkable regenerative capacity, to answer this question. They compared and modulated the injury responses of these mice and common laboratory mice, that show scarring upon injury. This revealed that ERK signalling is a crucial molecular switch between scarring and regeneration. The results of this study will be published on April 26th in the scientific journal Science Advances and imply that modulation of ERK signalling could potentially be used to stimulate regeneration in a clinical setting.