Rabbit Anti-Human CDC42EP1 monoclonal antibody for WB. MSE55 also known as Borg5 or binder of Rho GTPases 5 is a Cdc42 effector protein that induces long cellular extensions in fibroblasts. MSE55 also increases and mediates actin cytoskeleton reorganization at the plasma membrane. MSE55 is a nonkinase CRIB (Cdc42/Rac interactive-binding) domain-containing molecule. An intact CRIB domain is required for the GTP-dependent binding of MSE55 to Cdc42. MSE55 is expressed in a tissue-specific manner in endothelial and bone marrow stromal cells. MSE55 may have a functional role in hematopoiesis or as a negative regulator of Rho GTPase signaling.