Caveolae: Stable Membrane Domains with a Potential for Internalization

The role of caveolae in endocytosis is hotly debated. Here, we argue that most caveolae are stable microdomains at the cell surface. Only a small fraction of caveolae is constitutively internalized, leading to a quantitatively minor uptake of ligands and receptors. In addition, we suggest that a more pronounced downregulation of caveolae from the plasma membrane can occur, presumably stimulated by receptor cross‐linking and clustering in caveolae. Finally, we propose that future studies dealing with internalization of caveolae should actually document such internalization and include kinetic data.