Rac and Rho compete to cooperate

摘要

Epithelial cells change their shape and re- model their apical cell-cell junctions during tissue morphogenesis. Rho and Rac GTPases control these processes by regulating myo- sin contractility. Genetic evidence, for ex- ample, suggests that RhoA and Rac1 path- ways work in parallel to promote the elon- gation of early C. elegans embryos. Yet, within individual cells, these two pathways tend to antagonize each other. Martin et al. resolve this conundrum by analyzing the behavior of individual epidermal cells during embryonic elongation (1).