(A and B) Krt15-CrePR1 R26^mT/mG mice were injected daily with 0.5 mg RU486 for 5 consecutive days and sacrificed at listed time points. (A) Colocalization of Krt15⁺ (GFP) cells with p63 (basal cell marker) and K13 (suprabasal cell marker). Magnifications of regions of interest are displayed in a yellow rectangle. (B) Colocalization of Krt15⁺ (GFP) cells with Ki-67. Magnifications of regions of interest are displayed in a yellow rectangle. Arrows indicate colocalization events. (C and D) Krt15-CrePR1 R26^mT/mG mice were injected once with 0.5 mg RU486 and sacrificed 1, 2, 3, and 5 days after. (D) The percentage of Ki-67⁺/GFP⁺ basal cells was determined. Graph represents mean odds ratios ± SEM versus D1 (n = 2–4 mice at each time point; cross sections of 4 different regions of the esophagus were analyzed for each mouse). *P ≤ 0.05 vs. D1 and ^#P ≤ 0.05 vs. D2 using z test. (E and F) Krt15-CrePR1 R26^mT/mG mice were injected once with 0.5 mg RU486 and sacrificed 1 day after. The percentage of Ki-67⁺ cells at each position surrounding the GFP (Krt15⁺) cells (position 0) was determined. Graph represents mean ± SEM (n = 4 mice; cross sections of 4 different regions of the esophagus were analyzed for each mouse); probability of having Ki-67⁺ cells in position 1 to 10 vs. position 0 was determined using χ² test: χ²(10) = 20.44, P = 0.025. (G) Krt15-CrePR1 R26^mT/mG mice were injected once with 0.5 mg RU486 and sacrificed 24 or 48 hours after. Mice were also injected with EdU 1.5 hours before sacrifice. Percentage of EdU⁺ cells among Krt15^– and Krt15⁺ basal cells was determined by flow cytometry. Graph represents mean ± SEM (n = 4 mice per group, *P < 0.05 [48 vs. 24 hours] and ^#P < 0.05 [Krt15⁺ vs. Krt15^–], using Wald χ² test). Dotted line marks the basement membrane. Scale bars: 50 μm.