Inhibition of CXCL12-mediated chemotaxis in primary human B-CLL cells. Primary leukemic cells isolated from patients with B-CLL were treated with PZ-218, PZ-210, or plerixafor (AMD, 0.1-10μM) and migration (A) and chemotaxis (B) toward CXCL12 was measured. Chemotaxis/migration of vehicle-treated cells to CXCL12 was set at 100%. All data are expressed as means ± SEM (n = 4) with assays done in triplicate or quadruplicate. **P < .01 compared with CXCL12-treated cells.