Caveolae and signaling.

Caveolae, cholesterol-rich invaginations of the plasma membrane, have been implicated as scaffolds where signaling complexes are assembled, and as portals to which recycling or newly synthesized free cholesterol is transported prior to efflux or redistribution. New data indicate that these functions may be related; membrane cholesterol content can regulate receptor-mediated signal transduction, while signals responding to membrane cholesterol levels may reach the nucleus via a parallel kinase-dependent pathway. This information from both sources may be integrated at the nuclear level to control complex biological functions such as locomotion and cell division.