Functions as guanine nucleotide exchange factor for RAC1. May play a role in semaphorin signaling. Plays a role in the assembly and disassembly of dendritic filopodia, the formation of dendritic spines, regulation of dendrite length and ultimately the formation of synapses (By similarity). Interacts with CADM1. Interacts with RAC1 (By similarity). Recruited to the cell membrane via interaction with CADM1. Detected in cAMP-treated chondrocytes, but not in untreated chondrocytes. Detected in fetal brain, heart and spleen, and in adult testis, kidney and lung. Up-regulated in response to cAMP in cultured embryonic chondrocytes. Intramolecular interaction between the DH domain and the PH domains can stabilize the protein in an autoinhibited conformation.