CDC42SE2 (CDC42 small effector 2) is a cytoskeletal regulatory protein that functions downstream of CDC42 to organize the actin cytoskeleton and induce actin filament assembly [UniProt]. In activated T cells, it may facilitate CDC42-mediated F-actin accumulation at the immunological synapse, while in macrophages it may participate in early contractile events during phagocytosis [UniProt]. CDC42SE2 acts as a signaling adaptor protein capable of altering CDC42-induced cell shape changes [UniProt]. Diseases associated with CDC42SE2 include colorectal cancer, where a genetic variant (rs12522693) at the CDC42SE2-CHSY3 locus on chromosome 5.3 increases susceptibility in Han Chinese populations 1. CDC42SE2 has also been identified in gene fusion events: a CDC42SE2-BRAF fusion was discovered in anaplastic pleomorphic xanthoastrocytoma (APXA), a rare pediatric glioma, and in S100/CD34 co-expressing soft tissue tumors, suggesting potential involvement in oncogenic transformation 23. Additionally, CDC42SE2 methylation in nasal epithelium has been associated with atopic asthma in children and adolescents 4, and differential expression of CDC42SE2 has been identified in gastrointestinal diseases including ulcerative colitis 5. CDC42SE2 may also modulate sensitivity to proteasome inhibitors in multiple myeloma 6.