IQGAP2 is a scaffold protein that regulates cellular signaling and cytoskeletal dynamics through multiple molecular mechanisms. Primary Function: IQGAP2 binds activated CDC42 and RAC1 small GTPases but lacks intrinsic GTPase-activating activity, instead modulating their signaling through alternative mechanisms 1. The protein contains conserved domains including an N-terminal calponin homology motif for actin binding, IQ motifs for calmodulin interaction, and a RasGAP homology domain 1. Mechanism: IQGAP2 associates with calmodulin through its IQ-motifs in a calcium-dependent manner 2, and functions as a scaffold bridging receptor signaling to intracellular outcomes 3. Disease Relevance: IQGAP2 functions as a tumor suppressor in multiple cancers. Reduced IQGAP2 expression in breast cancer promotes epithelial-mesenchymal transition and inhibits apoptosis via MEK-ERK and p38 pathway dysregulation 4. Loss-of-function variants associate with altered blood cell traits 5, and reduced hippocampal IQGAP2 correlates with Alzheimer's disease 6. Clinical Significance: IQGAP2 deficiency increases blood-brain barrier permeability and leukocyte infiltration into the CNS 6, highlighting its role in immune privilege maintenance. The protein represents a therapeutic target for cancer intervention through restoration of tumor-suppressive functions.