The same spatiotemporal pattern of localization was observed for a farnesylated/palmitoylated protein containing D-amino acids at the palmitoylation site , suggesting that depalmitoylation does not require a specific recognition sequence around this region. How would a cytosolic thioesterase like Apt1 recognize membrane-embedded thioester linkages without the presence of a defined consensus sequence? It is clear that much more research on Apt1 is required and that the identity of novel inhibitors will greatly facilitate this. One interesting angle is to determine whether the turnover of palmitate on cellular proteins correlates with the ability of Apt1 to promote depalmitoylation in vitro. For example, caveolin is not a substrate of Apt1 in vitro and does not undergo rapid dynamic palmitoylation in cells (Parat and Fox, 2001) , and the reverse is obviously true for proteins such as eNOS and Ras.