Figure 5. Comparison of absolute ALK copy numbers determined by ddPCR for neuroblastoma cell lines.

Genomic DNA was extracted from cultured cells and fragmented by sonication before ALK copy number was determined by ddPCR (white circles, mean indicated by the line and SD indicated by the whiskers; n = 3). Cell-free DNA was purified from medium conditioned by the cell lines, and copy numbers were detected by ddPCR (blue squares, mean indicated by the line and SD indicated by the whiskers; n ≥ 1). Dashed lines indicate thresholds for diploid (2 copies), gain (≥ 3 copies) and amplified (> 8 copies) status.