Effects of de-induction of <i>PyMT</i> and <i>luciferase</i> in the acinar cell carcinomas of <i>Pdx1-tTA</i>; <i>tet-o-PyMT-IRES-Luc</i> bitransgenic mice.

<p>(A) Bioluminescence intensities from 4 <i>Pdx1-tTA</i>; <i>tet-o-PyMT-IRES-Luc</i> bitransgenic mice before and after being placed on doxycycline for 1 to 4 days; each symbol denotes a different mouse. Bioluminescent images of one mouse (represented by ▪) are shown on the right during induction and 1 and 4 days after addition of doxycycline. (B) De-induction of <i>PyMT</i> in <i>Pdx1-tTA</i>; <i>tet-o-PyMT-IRES-Luc</i> bitransgenic mice with acinar cell carcinomas causes tumor regression. Hematoxylin and eosin stain of pancreatic sections from <i>Pdx1-tTA</i>; <i>tet-o-PyMT-IRES-Luc</i> bitransgenic mice with strong luciferase activity (>10⁸ photons/sec) before and after being placed on doxycycline for 2, 12, and 15 weeks. Original magnification, 5×. The ages of the mice when sacrificed were indicated.