The expression of two sets of genes, Mafa/Mafb and Ucn3/Crh, that markedly differ in their expression between alpha and beta cells in mouse (A) and human (B) islets. Mafa is restricted to beta cells of both species, while Mafb is selectively expressed in mouse alpha cells (A) but expressed in human beta cells as well (B). Ucn3 is highly selective for mouse beta cells while Crh is detected in neither mouse islet population (A, C, D). By contrast, UCN3 expression is abundant in human alpha and beta cells, while CRH is enriched in human alpha cells (B, E, F). Human RNA-seq data from [78]. Figure originally published in [16] under a Creative Commons Attribution 4.0 International License and reused without alteration.