The telomerase assay was carried out using the TeloChaser
(TOYOBO). This kit is based on Stretch PCR method (Tatematsu et al.,
1996), which is modified from the original, PCR-based TRAP (telomeric
repeat amplification protocol) assay (Kim et al., 1994). In both assays,
telomeric repeats are added onto the 3'-end of a substrate oligonucleotide
by telomerase in tissue extract.