// Workers AI · dad joke modeWhat did CA4 say to CA2? You're a factor behind.

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

CA-4 may refer to:

• 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 may refer to:

• Ca4 line, a regional Catalonia railway line connecting Barcelona and Lleida-Pirineus

Ca₄ may refer to:

• 4 atoms of Calcium

Ca.4 may refer to:

• Caproni Ca.4, an Italian heavy bomber of the World War I era