Summary of the percentage of stem and progenitor cell populations labeled with ¹²⁵I-cytokine (A) and the number of receptors expressed on positive cells (B). The following symbols represent the cytokine receptors analyzed: (□) M-CSF; (▪) IL-6; (○) IL-3; (•) G-CSF; (▵) GM-CSF; (▴) IL-1; and (+) LIF.