ARHGEF4 (Rho guanine nucleotide exchange factor 4) is a brain-enriched guanine nucleotide exchange factor that activates small GTPases including Rac1 and Cdc42 12. The protein regulates actin cytoskeleton reorganization and cellular morphology, controlling the formation of membrane protrusions, filopodia, and podosomes in various cell types 23. ARHGEF4 functions through ERK1/2 and GSK-3α/β signaling pathways to promote cell motility and invasion 2. In hepatic stellate cells, ARHGEF4 specifically mediates actin cytoskeleton reorganization in 3D collagen matrices, promoting podosome-related gene expression 3. The gene is clinically significant in multiple contexts: high ARHGEF4 expression correlates with poor prognosis and increased invasiveness in pancreatic cancer 2, serves as a biomarker for progressive primary open-angle glaucoma 4, and is involved in cisplatin resistance in lung cancer 5. Genomic deletions affecting ARHGEF4 are associated with neurodevelopmental disorders including ADHD, intellectual disability, and epilepsy 6. Additionally, ARHGEF4 methylation patterns are altered in maternal asthma and serve as tumor purity markers in esophageal cancer 78.