state divisions are one of the most effective tools for political space organizing. the background of dividing the territory of the country into smaller units in iran may be historically traced back to the formation of the first territorial state by achaemenids. the role and function of state divisions, its relationship to national survival, facilitation of exerting the government’s will, a bal...

Regulation of stem cell division is of particular interest, both for studies of development and for stem cell therapeutics. In this issue of Neuron, Bello et al. show that the number of divisions of Drosophila neural stem cells is limited, in a region-specific manner, by regulated apoptosis in response to a pulse of expression of the Hox gene abdominal-A (abdA).