Rap2A links intestinal cell polarity to brush border formation

Microvilli are essential for the function of intestinal cells. Bos and colleagues have found that the polarity kinase LKB-1 induces PtdIns(4,5)P2 enrichment at the apical membrane. This leads to the successive accumulation of phosphatidic acid and the small GTPase Rap2A with its GEF and its effectors. These, in turn, trigger the changes in the actin cytoskeleton responsible for microvilli formation.