TRAP results in two breast tumours (TRAP +ve) and adjacent non-cancerous breast tissue (TRAP -ve). "Positive and negative" represent controls (squamous cell carcinoma of the head and neck and lysis buffer respectively). This figure shows the electrophoresis of PCR products on 10% polyacrylamide gel visualized by phospho-imager. Telomerase activity is indicated by the generation of a DNA ladder. The intensity of the bands correlates with telomerase activity.