What is left behind--quality control in germ cell migration.

Cell differentiation, cell proliferation, cell death, and cell migration are tightly controlled during animal development and adult homeostasis. Failure to regulate these processes can result in tumor formation and metastasis. Aberrant cells are therefore often cleared by induction of cell death. Recent work has elucidated the mechanism of elimination of mouse primordial germ cells that fail to migrate properly and highlights the similarity of this mechanism to those governing the same phenomenon in Drosophila. In addition, these studies underscore the different functions a single signaling pathway can have in controlling cell survival, cell proliferation, and cell migration during different phases of development.