[en] The research of the Mammalian Cell Biology Group continues to be based upon the cultivation of mammalian cells in vitro. Although a series of diverse topics is being pursued, these have in common efforts to understand the cellular and molecular biology of functional changes produced by environmental agents including ionizing radiation, nonionizing radiation, and various chemicals. Although the group maintains a considerable interest in the radiobiology of ionizing radiation, its perspectives have broadened and shifted: first, to include the biological properties of various spectra of fast neutrons as well as x-rays; second, to inquire about sunlight effects and the interaction of sunlight with ionizing radiation damage; third, to include end effects such as neoplastic transformation in addition to cell killing and DNA damage; and fourth, to initiate studies of the action of chemical carcinogens by themselves and in conjunction with radiation