Stem cells possess a tremendous medical potential, especially towards regenerative medicine and cancerology. However, to harness their full potential, we must understand exactly how stem cells work. We are particularly interested in the homeostatic mechanism that links stem cell proliferation rates to the demand for their differentiated cellular progeny in the tissue they serve. We mainly use the germline stem cells of the nematode C. elegans as a model to efficiently dissect homeostatic signaling.