This gene encodes a member of the IQGAP family. The protein contains four IQ domains, one calponin homology domain, one Ras-GAP domain and one WW domain. It interacts with components of the cytoskeleton such as the formin Dia1 (mDia1), with cell adhesion molecules (CAMs), and with several signaling molecules to regulate cell morphology and motility. For example, IQGAP1 expression is necessary for neuronal process outgrowth on the cell adhesion molecule PTPmu (PTPRM). Expression of the protein is upregulated by gene amplification in two gastric cancer cell lines and its over-expression and distinct membrane localisation is also observed in a range of tumours.