The overall objective of the proposed research project is to define possible controls during normal and neoplastic growth. (1) The physical and enzymic properties of homogeneous DNA polymerase and from HeLa cells will be characterized. (2) Stimulatory factors for DNA biosynthesis in vitro will be isolated and characterized. (3) The characterization of a multi-enzyme complex for DNA biosynthesis in rat liver and HeLa cells will be continued. (4) The physical and enzymic properties of ribosome-associated DNA polymerase in rat liver will be characterized.