Noggin and bFGF cooperate to maintain the pluripotency of human embryonic stem cells in the absence of feeder layers - Guangwen Wang; Hong Zhang; Yang Zhao; Jian Li; Jun Cai; Peigang Wang; Sha Meng; Jingbo Feng; Chenglin Miao; Mingxiao Ding; Dongsheng Li; Hongkui Deng (Biochemical and Biophysical Research Communications, 2005)