A schematic demonstrating a representative cell moving towards the CCL2 protein gradient is shown in Fig. 4B. Similar findings were demonstrated with a second neuroblastoma cell line, SK-N-SH (Supplementary Fig. S3). A monocyte migration assay was performed using Boyden transwell chambers with monocytes in the upper chamber and CCL2 in the lower chamber. The gene discussed is CCL2; the disease is neuroblastoma.