Standard TRAP Assay

The polymerase chain reaction (PCR) based telomeric repeat amplification protocol (TRAP) assay, to detect telomerase activity was originated by Kim et al. in late 1994 (1 ) and revolutionized the field of telomere/telomerase research in aging, but particularly in cancer. Thus, the TRAP assay has provided the stimulus for the current interest in the detection of telomerase activity in a wide variety of human malignancies with regard to its potential clinical utility, as a diagnostic adjunct in the early diagnosis of malignancy, as a potential prognostic indicator (2 -7 ) or as a means to identify telomerase inhibitors (7 , 8 ). Previously, investigators had to rely on the elaborate conventional primer extension assay for detecting telomerase activity, which requires large amounts of telomerasepositive cells (2�10⁸ ), thus limiting the number of primary human specimens that could be examined easily (9 ,10 ). A major problem with the conventional assay is also the weak signal strength, necessitating extensive autoradiographic exposure times (more than a week). Moreover, enhancement of signal would require enrichment of the telomerase fraction and additional time consumption (11 ).