CA4

CA4, CA-4, or Ca4 may refer to:

Carbonic anhydrase 4, an enzyme that in humans is encoded by the CA4 gene Cornu Ammonis region 4, a region of the hippocampus United States Court of Appeals for the Fourth Circuit CAC CA-4, a 1941 Australian bomber aircraft USS Pittsburgh (CA-4), a 1901 United States Navy armored cruiser California's 4th congressional district California State Route 4 Central America-4 Border Control Agreement, a boundary treaty between Guatemala, El Salvador, Honduras, and Nicaragua Combretastatin A-4, a natural polyphenol Ca4 line, a regional Catalonia railway line connecting Barcelona and Lleida-Pirineus 4 atoms of Calcium Caproni Ca.4, an Italian heavy bomber of the World War I era