Sensitivity of nested polymerase chain reaction assay to tumor-specific markers in hepatocellular carcinoma cell lines. Lanes 1-4: 1 × 103, 1 × 102, 1 × 101 and 1 × 100 hepatoma cells detected by nested reverse transcripts-polymerase chain reaction using melanoma antigen-1 (MAGE-1), synovial sarcoma X breakpoint-1 (SSX-1), cancer-testis-associated protein of 11 kDa (CTp11), and β2-microglobin; Lane 5: Peripheral blood mononuclear cells (PBMC) from healthy donors only; Lane 6: negative control; Lane M: Molecular marker, 100 bp DNA ladder (Gibco).