Fig. 1

Schematic representation of the Delta-Notch signaling pathway. The upper panel shows the three-dimensional structure of the liver. The middle panel shows a plane perpendicular to the portal vein. Note that the PV cell expresses high amounts of Delta ligand (shown in red) and is in direct contact with a cholangiocyte. The bottom panel shows the two types of interaction of the Delta ligand and Notch receptor (shown in blue). When these two components on the opposing cell membrane interact (trans-interaction), the reporter target gene is expressed. Another type of interaction called cis-interaction involves Delta ligands inhibiting signal transduction from Notch receptors on the same cell membrane