SDF-1α induces loss of microvilli concurrent with polarization. Scanning electron micrographs from field emission SEM of human PBT cells before (A) and after (B) 1 minute of stimulation in suspension with 100 ng/mL SDF-1α. Cells were stimulated, fixed, and processed for SEM as described in “Materials and methods.” The arrow indicates the ruffled leading edge of the polarized lymphocyte. Bar represents 2.5 μm.