As mammalian tissues have limited regenerative capacity, understanding how regeneration processes are controlled has considerable clinical potential. Kang et al. investigated regulatory sequences associated with the activation of regenerative programmes. By studying regenerating tissues in zebrafish, they identified a 1.3 kb sequence (termed LEN) in the enhancer region of the leptin b gene (lepb), which, when placed upstream of reporter genes, could drive their robust expression selectively following injury. Using LEN and the minimal lepb promoter, the authors were able to induce ectopic expression of both pro- and anti-regenerative factors in the injured tissues and to modulate the regeneration process. Importantly, LEN could also drive reporter gene expression following injury in mice, opening exciting new avenues in the field of regenerative biology.