Phosphoinositide 3-kinases (PI 3-kinases) phosphorylate the 3 position of the inositol ring in phosphatidylinositol and other phosphoinositides, allowing them to recruit proteins containing pleckstrin homology (PH), FYVE and other lipid-binding domains to cellular membranes. The class I, class II and class III PI 3-kinases exhibit differing substrate requirements, modes of regulation and subcellular locations. To help keep track of these, Michael Fry and co-workers summarize the roles of the various members of the PI 3-kinase superfamily in Cell Science at a Glance, including details of their regulatory subunits, their locations and a phylogenetic tree (see p. 3037).