Expression of cell surface markers (c-kit, Thy1.2, and Sca1) on Lin⁻ cells. (A) Two-color flow cytometric analysis of lin⁻ cells stained for c-kit, Thy1.2, and Sca-1. Numbers represent percent of cells in the given areas. (B) Fluorescence histogram of Lin⁻Thy⁻Sca⁻ cells (boxed area in A) analyzed for c-kit expression. The dotted line indicates an isotype control. Lines indicate the gate for the collection of c-kit^low and c-kit^high cells.