Several key transcription factors are necessary for alpha cell development in the pancreas. In this study, we describe the expression of Inhibition of DNA-binding protein 1 (Id1) in the developing as well as the normal adult pancreas. We found co-expression of Id1 with bone morphogenetic protein (BMP) receptor in alpha cells. Inhibition of BMP4 signaling with a specific neutralizing antibody slightly decreases the proportion of glucagon cells in the adult pancreas but had a significant effect in a model of pancreas regeneration. In late embryonic pancreas, Id1 co-localized with GATA4, a transcription factor known for its critical function in glucagon cell development. However, in early postnatal period, the expression of Id1 and GATA4 diverged with Id1 identified in glucagon cells and GATA4 restricted to the acinar pancreas.