Keeping up with the neighbors: Coordinating cell fate within and across epidermal layers.

Stratified epithelia such as the skin epidermis face a formidable challenge: maintaining a functional barrier in the face of continuous cellular turnover. Coping with this challenge means that keratinocytes must be exquisitely sensitive to the identity, position, and behavior of their neighbors. This review highlights emerging work on how cell fates are coordinated across the layers of the interfollicular epidermis during homeostatic regeneration, with a particular focus on how density changes, local signaling patterns, and mechanical cues control progenitor behaviors in the basal layer and facilitate the ordered progression of terminal differentiation in the suprabasal layers above.