Epithelia act as physical barriers that protect living organisms from the surrounding environment. Therefore, the organization and homeostasis in epithelial tissues requires robust mechanisms that assure their integrity in a variety of biological situations, such as normal cell turnover, inflammation and injury. The cell biology of wound healing has started to be understood but there are still many open questions and the signaling cascades that regulate this process are largely unknown. An intriguing and crucial question is what is the nature of the earliest signals that activate the different events of a wound response. In this project, we will study the signaling pathways required for the activation of the wound response. Our main focus will be the role of EGF/ERK signaling, which we propose to be one of the first pathways to be activated in this process. We also plan to determine the primary signals activating the wound response cascades. We will use the Drosophila embryonic and pupal epithelia as our primary model systems, but will also investigate whether these signaling mechanisms are conserved in vertebrates, by studying the wound healing process in zebrafish embryonic epithelia.