Fig1C. Copyright: Reprinted with permission from Cell Press from [doi:10.1016/S0896-6273(02)01172-8] Neuron 37: 197-207, Wu HH; Ivkovic S; Murray RC; Jaramillo S; Lyons KM; Johnson JE; Calof AL, Autoregulation of Neurogenesis by GDF11. Copyright 2003