Original sentence: He took a position in 1968 as chief of the National Cancer Institute's Laboratory of Viral Carcinogenesis, staying tehre until his retirement in 1982.In a paper published in the Proceedings of the National Academy of Sciences'' in 1969, Huebner advanced his theory that oncogenes, then only a hypothetical construct, could cause normal cells ro mutate and become cancerous
Edited sentence: He took a position in 1968 as chief of the National Cancer Institute's Laboratory of Viral Carcinogenesis, staying there until his retirement in 1982.In a paper published in the Proceedings of the National Academy of Sciences'' in 1969, Huebner advanced his theory that oncogenes, then only a hypothetical construct, could cause normal cells to mutate and become cancerous