The adaptable lin-39

Comparative studies of nematode development provide a powerful framework for investigating the evolution of developmental mechanisms. A recent report also demonstrates how comparative work can inform our understanding of basic developmental signaling pathways. In particular, investigation of the differences in vulva development between Caenorhabditis elegans and Pristionchus pacificus has clarified the molecular relationship between an epidermal growth factor–Ras–MAP kinase signaling pathway and downstream Hox transcription factor activity.