(A) Cdc42 (grey) in complex with GEF Intersectin (cyan) (PDB:1KI1) with Switch I of Cdc42 (dark blue) and key interacting residues for small molecule inhibitors ZCL278 and ZCL376 (green); Thr35, Val36, Asp38, Asn39, Phe56 and Asp57 (B) Schematic representations of interactions between Cdc42 residues and molecules ZCL278, ZCL367 and CASIN. Interactions of ZCL278 include 2 hydrogen bonds with Thr35 and Asp57 and hydrophobic interactions with Thr35 and Val36. Interactions of ZCL367 involve 3 hydrogen bonds with Asp38, Asn39 and Asp57 and 2 hydrophobic interactions with Phe56 and Val36 of Cdc42. Interaction of CASIN involves a critical interaction with Met45 of Cdc42.