Our lab studies signal transduction by the phosphoinositides, a group of signaling molecules involved in hormone and growth factor signaling, membrane trafficking, and probably many more functions. We are taking several approaches to identify novel functions for this interesting group of signaling molecules. One approach uses fluorescence microscopy of living mammalian cells to observe the behavior of each of the phosphoinositides in real-time. Another approach involves a proteomic screen to identify novel phosphoinositide-binding proteins. Both approaches have yielded new and unexpected functions for the phosphoinositides. We have many projects to study our new phosphoinositide binding proteins and to develop new approaches to study phosphoinositide function. Ultimately we expect this approach to yield new insights into the mechanism of hormonal signaling and perhaps to identify new therapeutic targets.