Background: SRGAP1/ARHGAP13 is a member of the srGAP family of proteins that contain a RhoGAP domain, an SH3 domain, and a Fes/CIP4 homology domain and interact with the intracellular domain of roundabout 1 (Robo1). Robo1 is the receptor for Slit signaling and is involved in neuronal cell migration and axon tract positioning. SRGAP1/ARHGAP13 functions to bind and decrease the level of active Cdc42 and RhoA small GTPases during Slit-Robo signaling.