(A) SDF-1 induces mobilization of intracellular calcium in CLL B cells (bold line). (B) The immature B-cell lines, Reh (bold line) and Nalm-6 (thin line). Increases of intracellular Ca²⁺ were recorded on a fluorometer after addition of 100 ng/mL SDF-1 to cells loaded with Indo-1. Adding ionomycin induced maximum release of intracellular Ca²⁺. A representative experiment of at least 3 is shown. (C) SDF-1 induces actin polymerization in CLL B cells, which can be inhibited by pertussis toxin. Intracellular F-actin was measured using FITC-labeled phalloidin in CD19-prelabeled CLL B cells (boxes) after the addition of 100 ng/mL SDF-1 at time 0. Results are shown as percent of intracellular F-actin relative to the value before the addition of SDF-1 and are the mean and SD of 3 independent experiments. Pertussis toxin inhibits actin polymerization in CLL B cells (diamonds).