Craniofacial defects in AP‐2 null mutant mice

AP‐2 is a recent significant addition to the list of transcription factors that have been demonstrated by targeted gene disruption to be essential for normal development. Two recent reports of AP‐2 null mutant mice (1,2) indicate that AP‐2 holds a key position in the network of genes and proteins controlling developmental pattern and morphogenesis, and that it is particularly important for development of the cranial region and for midline fusions.