To evaluate chemotactic migration of GBM cells or macrophages in the direction of CCL21, Transwell assays were performed:1.0 × 105 cells were plated in the top chambers in 150 μL of serum-free medium, with increasing concentrations of CCL21 (from 50 to 1000 ng/mL) or GBM conditioned medium in the bottom chambers. The gene discussed is CCL21; the disease is glioblastoma.