Figure 1.

Interplay of GTPases and the cytoskeleton in cellular barrier defects during gut inflammation. The intestinal epithelium and the endothelium establish two coordinated physical and immunological barriers. Increased barrier permeability is pathogenetically associated with inflammatory bowel diseases (IBDs). Different members of the families of small (lower brown) and large (upper blue) GTPases have recently been shown to regulate junctional and cytoskeletal dysfunctions both in epithelial and endothelial cells and, accordingly, may play an important role in IBD. It warrants further studies to determine whether cooperative, antagonistic, or redundant functions are exerted by the different GTPases.