Figure 1. Cytokeratin 20 and glyceraldehyde phosphate dehydrogenase (GAPDH) reverse transcriptase–polymerase chain reaction amplification products from blood samples obtained before, during, and after surgery from three patients undergoing hemihepatectomy for liver metastasis of colorectal carcinoma. W, water negative control; N, negative control (blood of healthy person); M, molecular weight marker; P, positive control (HT29 cells). Lanes 1–3, patient 1; lanes 4–6, patient 2; lanes 7–9, patient 3. Lanes 1, 4, and 7, before surgery; lanes 2, 5, and 8, during surgery; lanes 3, 6, and 9, after surgery.