Transwell migrational assay of bone marrow CD34+ cells, in vitro. Compared with diluent control, stromal cell derived factor-1 (SDF-1) and eotaxin stimulated a significant dose-dependent migrational response of CD34+ cells, which was optimal at 100 ng/ml and 500 ng/ml, respectively (*P < 0·05; **P < 0·01). The eotaxin-, but not SDF-1-stimulated progenitor cell migratory response was completely attenuated in the presence of anti-CC chemokine receptor 3 (CCR3). Data are expressed as mean ± standard error of the mean (SEM) of six separate experiments performed in duplicate.