CDC42EP1 (CDC42 effector protein 1) is a Cdc42-binding protein that regulates actin cytoskeleton organization and cell morphology. The protein localizes to focal adhesions, adherens junctions, and the plasma membrane, where it associates with septin-7, villin, and myosin IIA to coordinate cytoskeletal dynamics 1. In epithelial cells, CDC42EP1 restricts contractility and motility while promoting lateral F-actin cortex development and columnar cell morphology; its depletion stimulates stress fibers and cell migration 2. During Salmonella infection, CDC42EP1 is rapidly recruited to bacterial entry sites and subsequently associates with Salmonella-containing vacuoles, contributing to intracellular bacterial replication rather than initial invasion 3. CDC42EP1 dysfunction associates with multiple diseases: it is downregulated in oral squamous cell carcinoma 4, dysregulated in the circRNA/miRNA axis promoting epithelial-mesenchymal transition (EMT) in endometriosis 5, and identified as a prominent cancer-predisposing mutation in parathyroid carcinoma 6. Additionally, CDC42EP1 represents part of a ten-gene signature associated with EBV reactivation and poor prognosis in nasopharyngeal carcinoma through EMT and metabolic reprogramming pathways 7. These findings establish CDC42EP1 as a key regulator of cytoskeletal architecture with important roles in infection responses, epithelial homeostasis, and cancer progression.