The proposal requests funds to purchase an AB 3730XL DNA sequencer, to replace two aging AB 377 instruments. It would be housed in the USC/Norris Comprehensive Cancer Center Microchemistry Core Laboratory, which offers a DNA sequencing service to peer-reviewed investigators. Acquisition of this new instrument will ensure that researchers at the University of Southern California have ready access to state-of-the-art DNA sequencing. This is essential in their endeavors to study fundamental mechanisms such as gene regulation, signal transduction, and DNA repair in normal and neoplastic cells. In addition, it will also advance the understanding of the genetic basis of disease, the design of vaccines and the development of therapies in the treatment of cancer, graft rejection and autoimmunity. ? ?