Proceedings of the National Academy of Sciences of the United States of America Proceedings of the National Academy of Sciences of the United States of America 105 (2008) 38 Proceedings of the National Academy of Sciences of the United States of America, 105(38), 14308-14312 Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences, 2008, 105 (38), pp.14308-14312. ⟨10.1073/pnas.0802430105⟩