Coexpression of Pdx1 and betacellulin in mesenchymal stem cells could promote the differentiation of nestin-positive epithelium-like progenitors and pancreatic islet-like spheroids - Lisha Li; Furong Li; Hui Qi; Gao Feng; Kehu Yuan; Hongkui Deng; Hanxin Zhou (Stem Cells and Development, 2008)