The chemotactic compass

Cells have an amazing ability to sense very shallow gradients of chemoattractants and move directionally. This fundamental process is critical for development and numerous disease states. Dictyostelium has emerged as one of the best understood model systems for elucidating the complex signaling pathways that drive chemotaxis. This review focuses on the signaling mechanisms regulating directed migration and discusses the role of polarity and development on our current understanding of this process. We highlight new findings using a second chemoattractant, folic acid and suggest that this chemical cue should be used when a developmental defect is suspected. We also speculate on recent studies which suggest that researchers should use our new understanding of the temporal and spatial relationships of signaling and cytoskeletal proteins to guide future experiments.