Fig. 1

a Left: Flow cytometry side scatter (SSC: x-axis) vs. forward scatter (FSC: y-axis) plot, showing single cells isolated from the mouse lung. Middle: expression levels of lineage-specific cell surface markers on these cells (x-axis); Lin^neg cells were sorted from the APC-negative fraction (red rectangle). Right: Histogram showing platelet-derived growth factor receptor A (PDGFRA) expression levels on lin^neg cells (x-axis); representative results are presented in all panels. b Two hundred cells of each indicated population were cultured. The numbers of colonies developing from pulmonary single cells (Pu), lin^neg, lin^negPDGFRA^neg, lin^negPDGFRA^low, and lin^negPDGFRA^high cells at day 7 after sorting are presented. All experiments were performed in triplicate, and means ± standard deviations of the results obtained in three independent experiments are presented; **P < 0.01. c Representative flow cytometry plot showing the expression of Thy-1 and Sca-1 on lin^negPDGFRA^high cells. A-, B-, and C-type fibroblasts indicate lin^negPDGFRA^highSca-1^highThy-1^low, lin^negPDGFRA^highSca-1^highThy-1^high, and lin^negPDGFRA^highSca-1^low cells, respectively