Cxcr4flox/flox / Lck-Cre mouse-derived T cells show impaired chemotaxis toward SDF-1. The chemotaxis toward SDF-1 of T cells from Cxcr4+/+/Lck-Cre mice or Cxcr4flox/flox/Lck-Cre were assessed with in vitro chemotaxis assays, as described in Materials and methods. Representative results in at least two independent experiments are shown. (a) Chemotaxis of thymocytes to SDF-1 or medium was compared between Cxcr4+/+/Lck-Cre mice and Cxcr4flox/flox/Lck-Cre mice. *P < 0.05, by Student's t-test. (b) Chemotaxis of purified T cells from LNs was assessed. Results are shown as mean ± SD of triplicate determinations and are representative of at least two similar experiments. *P < 0.05, by Student's t-test Open columns indicate numbers of cells migrated into the chambers filled with medium only, and black columns, into the chambers with the medium supplemented with SDF-1 (100 ng/ml).