Caveolae are specialised domains of the plasma membrane that are implicated in the sequestration of a variety of lipid and protein molecules. It has been suggested that these important cellular organelles have a pivotal role in such diverse biochemical processes as lipid metabolism, growth regulation, signal transduction, and apoptosis. Caveolin interacts with and regulates heterotrimeric G proteins. Currently, there are three members of the caveolin multigene family which are known to encode 21 to 24 kDa integral membrane proteins that comprise the major structural component of the caveolar membrane in vivo. Caveolin 2 protein is abundantly expressed in fibroblasts and differentiated adipocytes, smooth and skeletal muscle, and endothelial cells. The expression of caveolin 1 is similar to that of caveolin 2 while caveolin 3 expression appears to be limited to muscle tissue types.