Acts as a RAC1 guanine nucleotide exchange factor (GEF) and can induce membrane ruffling. Functions in cell migration, attachment and cell spreading. Promotes targeting of RAC1 to focal adhesions. May function as a positive regulator of apoptosis. Downstream of NMDA receptors and CaMKK-CaMK1 signaling cascade, promotes the formation of spines and synapses in hippocampal neurons (By similarity). Interacts with SCRIB; interaction is direct and may play a role in regulation of apoptosis (By similarity). Interacts with PAK kinases through the SH3 domain. Interacts with GIT1 and probably TGFB1I1. Interacts with ITCH and PARVB. Interacts with FRMPD4 (via N-terminus). Interacts with CaMK1. Interacts with PTK2/FAK1 and RAC1. Interacts with BIN2 (By similarity). Interacts with YWHAZ (By similarity). Detected at cell adhesions. A small proportion is detected at focal adhesions. Phosphorylated on Ser-516 by CaMK1; enhancement of GEF activity and downstream activation of RAC1. Phosphorylated by PTK2/FAK1; this promotes interaction with RAC1 (By similarity).