BMSSCs express functional SDF-1 receptors. (A) RT-PCR analysis demonstrating the relative expression of CXCR4 and GAPDH transcripts in total RNA isolated from either primary BMSSC cultures or the human osteosarcoma cell line, MG63. (B) Single-cell suspensions of cultured BMSSCs were incubated with either a mouse anti–human CXCR4 antibody or the isotype-matched control antibody, 1A6.11 followed by a goat anti–mouse IgG₁ FITC-conjugated antibody. A representative histogram depicts the level of cell surface expression of CXCR4 (solid line) by BMSSCs relative to the control samples (dotted line) as assessed by flow cytometric analysis. (C) The graph demonstrates the levels of intracellular calcium measured in primary BMSSC cultures over time following the addition of human recombinant SDF-1α (30 ng/mL).