TERT and cancer: Telomerase, a complex of enzymes repressed in normal cells, is activated in the cancer cells and preserves the telomere of cancer cells.51 Telomerase complex consists of various enzymes; one of the most important is telomerase reverse transcriptase (TERT; hTERT for human) that becomes the rate-limiting step in telomerase activity.52 Telomerase is found in about 85% to 90% of all malignant tumors and become an interesting target for the anticancer drugs.53 Several natural compounds show anticancer activity by targeting replicative immortality of cancer cells (Table 4).