Model of liver-to-endocrine pancreas transdifferentiation. Expression of a modified form of Pdx1-Vp16 in hepatic stem (WB) cells activates multiple downstream TF genes associated with β-cell development and convert the WB cells into β-cell precursors. However, Pdx1-Vp16 failed to activate the following late-stage pancreatic transcription factors: Pax-4, Pax-6, Isl-1, and MafA, as well as the β-cell function-related genes SUR1, Kir6.2, SNAP25, and IAPP. Functional β-like cells can be achieved by: (a) culturing them under long-term high-glucose medium, (b) transplanting cells into diabetic (hyperglycemic) mice, and (c) activating Pax4 gene.