Constitutive expression of MIP-1 receptors on human CD34⁺ cells isolated from NBM, CB, and LP. Purified CD34⁺ cells were double-stained with biotinylated MIP-1 and antibodies specific for the CD34 antigen. Results are expressed as the percentage of CD34⁺ cells coexpressing MIP-1 receptors. Horizontal bars denote the median of n individual determinations.