Functions as a guanine nucleotide exchange factor (GEF) that promotes the exchange of GDP to GTP, converting inactive GDP-bound small GTPases into their active GTP-bound form (PubMed:12628187, PubMed:16464467). Involved in regulation of adherens junction between cells (PubMed:12628187). Plays a role in cell migration (PubMed:20679435). ; [Isoform 2]: Has a higher guanine nucleotide exchange factor activity compared to other isoforms.
