Fig. 1: The P2 BCSC subpopulation displays a dormant phenotype in the lungs.

a H&E staining (top) and distance from tumor edges to invasive fronts (bottom) after orthotopic injection of CA1h-P1 and CA1h-P2 cells (n = 15 random microscopic fields (RMFs) from 5 tumors each group). b, c Seeding and proliferation of MCF10CA1h and MCF10CA1a (b), or MCF10CA1h subpopulations (c) in lungs at 2–7 days after intravenous transplantation Shown are representative immunofluorescences (IF) images (left), a number of GFP⁺ tumor cells (middle) and EdU⁺ proportions of tumor cells (right); n = RMFs from 3 mice. The triangles indicate GFP and EdU double-positive cells. d–h Long-term analyses of lung metastasis after intravenous transplantation of cancer cells (n = 7, 8, 5, and 9 mice for MCF10CA1a, MCF10CA1h, CA1h-P1, and CA1h-P2, respectively). Shown are BLI quantification of pulmonary metastasis by CA1h-P1 and CA1h-P2 (d), percentages of mice with or without metastatic signal in lungs at week 14 (e), quantitation (top) and representative images (bottom) of pulmonary surface nodules (f), H&E (g), and IF (h) staining of lung tissue sections at week 20. H&E and IF staining in g, h were performed on lung sections of three mice in each group with similar results and representative images were shown. In a, g: L lung, P para-tumor, T tumor; dashed lines indicate tumor edges. Scale bar, 100 μm. Data represent mean ± SEM (a–c), mean ± SD (d), or mean with data points (f). Statistical significance was determined by a two-tailed unpaired t test (a–c, f), two-sided chi-square test (e), or two-sided Mann–Whitney test (d).