Telomerase expression by the cancer cell lines used in the study. The analysis was performed by real-time PCR performing 40 cycles of DNA amplifications; data are expressed as fluorescence intensity. (A) The blue, green, red, black, and pink lines correspond to the positive standards constituted by 1 × 10⁶, 1 × 10⁵, 1 × 10⁴, 1 × 10³, and 1 × 10² copies of hTERT RNA, respectively. The blue line corresponds to the negative control; the dark green line corresponds to the positive control provided by the kit manufacturer. (B) The gray, purple, orange, and blue lines correspond to the curves of hTERT cDNA amplification starting from RNA extracted from LnCap, Raji, Bjab, and T2 cell lines, respectively.