Much effort is being invested in defining the intrinsic and extrinsic factors that control stem cell maintenance and proliferation. Recent studies have identified a signaling hierarchy involved in coordinating the proliferation of germ line and somatic stem cells in the Drosophila ovary.
Department of Developmental Biology, Stanford University Medical School, Beckman Center B-373, 279 Campus Drive, Stanford, California 94305, USA. dljones@cmgm.stanford.edu