Early efforts to place the first cloned mammalian PIK-related kinase, FRAP,
into a conventional membrane to nuclear pathway met with little success. M
ore recent data suggest that members of the family of PIK-related kinases a
ct as intracellular sensors that govern radial. and horizontal pathways. Th
ese pathways can impinge upon classical membrane to nuclear pathways, as we
ll as components of the cell cycle machinery.