(A–C) Immunofluorescence staining of CK19 was conducted in the liver of R26RNotch/+ mice (A), Alb-CreERT2;R26RNotch/+ mice (B), and Alb-CreERT2;Hes1fl/fl mice (C) after 14 weeks of TAA administration. (D) The percentages of cells immunoreactive for CK19 in the liver of R26RNotch/+, Alb-CreERT2;R26RNotch/+, and Alb-CreERT2;Hes1fl/fl mice were calculated after counting approximately 3,000 cells per field of vision in 3 discontinuous liver tissue slides for 3 individual mice after 14 weeks of TAA administration. The data represent mean ± SD. (E) Immunofluorescence staining of CK19 was conducted in the liver of Alb-CreERT2;R26RYFP/Notch mice after 8 weeks of TAA administration. (F and G) Representative images of the liver from R26RNotch/+ mice (F) and Alb-CreERT2;R26RNotch/+ mice (G) after 14 weeks of TAA administration. Developing neoplastic nodules are only found in the liver of Alb-CreERT2;R26RNotch/+ mice. CV, central vein; PV, portal vein. DNA was stained with DAPI. Scale bars: 500 μm (A–C), 100 μm (E), and 5 mm (F and G).