Adeno-Associated Virus serotype 6 (AAV6) appears to be related to AAV1 by sequence analysis and shows the best transduction efficiency in pancreatic beta-cells compared to other AAV serotypes. AAV6 vectors are also particularly effective in the transduction of human prostate, breast, and liver cancer cells.These AAV particles constitutively express the firefly (Photinus pyralis) luciferase gene under the control of a CMV promoter. AAV transduction efficiency can easily be verified by measurement of luciferase activity.