Quite separately,the discovery of GPP (19) and IPP (20) aspotential ligands and substrates of SHIP2 is tantalizing, given therole of inactivating mutations of SHIP2 in opsismodysplasia, a skeletalchondroplasia,38 and the use of bisphosphonates,which target isoprenoid metabolism to prevent bone resorption.39 Here, IPP is linked to opsismodysplasia.