Fig. 1: Generation and characterization of Cre-induced ProTracer system.

a, b Schematic diagrams showing Dre-induced ProTracer (a) and Cre-induced fProTracer (b) for the genetic recording of cell proliferation. c Schematic diagram showing the experimental design for Alb-CreER induced fProTracer. Tam, tamoxifen. d Whole-mount liver images and immunostaining of liver sections of mice without Tam. e Whole-mount fluorescence images of livers collected at 2w, 6w, and 10w after Tam. f Immunostaining for GFP, GS, β-catenin, and E-cad on liver sections. g A cartoon image showing new hepatocyte generation highly enriched in zone 2. h Quantification of the percentage of GFP⁺ hepatocytes in each zone. Data were mean ± SEM; *P < 0.05. i A schematic diagram showing the experimental design for Krt5-CreER induced fProTracer. j Whole-mount fluorescent staining for GFP and Krt5 of mammary glands. k Flow cytometric analysis of GFP⁺ basal cells in mammary gland from mice treated with or without Tam. l Immunostaining for GFP and Krt5 on mammary tissue sections. Arrowheads, GFP⁺Krt5⁺ cells. m Quantification of the percentage of basal cells expressing GFP. Data were mean ± SEM; n = 5. n A schematic diagram showing the experimental design. BEC, basal epithelial cells. o Whole-mount fluorescent images of mammary glands. p Flow cytometric analysis of GFP⁺ basal cells from the mutant and control mice. q Immunostaining for Krt5 and GFP on mammary tissue sections. r Quantification of the percentage of GFP⁺ basal cells in mice at 3 weeks post Tam. Data were mean ± SEM; *P < 0.05. s A cartoon image shows the proliferation pattern of Krt5⁺ BECs in the mammary gland. Scale bars: white,100 μm; yellow, 1 mm. Each image is representative of five individual mouse samples.