Analysis of Lin⁻ adult bone marrow cells. The light scatter properties of the cells were measured (A), and two populations were identified, designated FSC^low and FSC^high. These populations were analyzed individually for the presence of c-Kit on the cell surface using PE-conjugated anti–c-Kit antibodies (B). The shaded area indicates control cells, whereas the open area indicates cells labeled with anti–c-Kit antibodies. Note that FL-2 measures PE.