Transmigration of cultured CD34⁺ cells was dependent on the expression of CXCR4.

CB CD34⁺ progenitor cells were stimulated ex vivo during 48 hours and assayed for transmigration across Fn-coated filters toward control medium (A,C) or MS-5 CM (B,D). Expression of CXCR4 was measured by FACS analysis in nonmigrating (A,B) and migrating cells (C,D). Staining with irrelevant isotype-matched IgG-PE (dotted lines) and anti-CXCR4–PE (solid lines) is shown in a representative experiment (of 7).