Reexpression of Neurog3 in duct-lining cells and reawakening of the EMT in Sst-Cre::Pax4-OE pancreata. (A–J) Immunofluorescence experiments were performed on pancreatic sections of 2-mo-old transgenics (B, D, F, H, and J) and matched controls (A, C, E, G, and I). Neurog3 was reexpressed in the ductal lining (B, yellow arrow) and epithelium (B, white arrow) of 2-mo-old transgenic mice but absent in matched-controls (A). Surprisingly, the mesenchymal marker Vimentin was largely expressed in the ductal lining epithelium of 2-mo-old transgenic animals (n > 5; D, F, H, and J) but weakly expressed in control mice (n > 5; C, E, G, and I), supporting the notion of an EMT reawakening after Pax4 expression in somatostatin⁺ cells. Moreover, vimentin-expressing cells labeled by BrdU were detected in Sst-Cre::Pax4-OE pancreata (inset in F), such cells being absent in matched controls (E). Further analyses of 2-mo-old mice revealed the presence of vimentin⁺/synaptophysin⁺ cells (G and H) and vimentin⁺/β-galactosidase⁺ cells (I and J) located close to adjacent ducts in transgenics. (K) Quantitative RT-PCR analyses confirmed our results with a mean 2.26 ± 0.30-fold increase in Neurog3 transcripts (n = 4) as well as an increase of 240% and 81% in the expression of IA1 and Snail2, respectively (n = 4). Further analyses revealed massive augmentations of Nestin and Sox11 expression in 2-mo-old transgenic pancreata (K). All values are depicted as mean ± SEM of n = 3 independent animals. Statistical analyses were performed with the Mann–Whitney test (**, P < 0.01; *, P < 0.05). For the purpose of clarity, in selected photographs, islets are outlined with dashed white lines and the ductal lumen with dashed yellow lines. Bars: 50 µm; (insets) 20 µm. DBA, dolichos biflorus agglutinin; Syn, synaptophysin.