1Department of Internal Medicine, Seoul National University Hospital, Seoul, South Korea
2Cancer Research Institute, Seoul National University, Seoul, South Korea
3Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul, South Korea
4Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, South Korea
5Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
6Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea