The Cdc42 effectors Gic1 and Gic2 regulate polarized post-Golgi secretion.

We conclude that Gic1/2 and Sec3 act in parallel to regulate polarized post-Golgi secretion, but this regulation is not solely controlled by their upstream factor Cdc42. Considering that N-terminal domain of Gic2 and Sec3 can bind to both Cdc42 and PtdIns(4,5)P2, the regulation of Gic protein and Sec3 on polarized secretion may also be controlled by PtdIns(4,5)P2. Further experiments need to be performed to test this hypothesis. Our findings provide important clues for understanding the molecular mechanism of cell polarity establishment in eukaryotic cells.