Fig. 4. Ela-CreERT2-based lineage tracing confirms acinar cell origin of metaplastic epithelium. (A,B) Phase-contrast images of X-gal stained Ela-CreERT2; R26R epithelium on initiation of explant culture, demonstrating mosaic expression of ß-gal reporter in acinar cells. (C-F) Phase-contrast (C,D) and bright-field (E,F) images of X-gal stained Ela-CreERT2; R26R epithelium on day 4 of culture. ß-Gal reporter marks acinar cell origin of metaplastic epithelium.