Fig3A, Todorovic V; Frendewey D; Gutstein DE; Chen Y; Freyer L; Finnegan E; Liu F; Murphy A; Valenzuela D; Yancopoulos G; Rifkin DB. 2007 [doi:10.1242/dev.008599] Copyright: This image is from Development and is displayed with the permission of the Company of Biologists Ltd. who owns the copyright.