When the telomeres become short enough, cell division stops and the cell soon dies. But cancer cells regrow their telomeres after every division. He and other researchers believe that telomere shortening is responsible for cellular aging and, eventually, cellular death. Most biologists do not accept so simple an explanation. Telomerase is the enzyme that essentially builds new telomeres.
Cancer cells produce plentiful telomerase.
In normal human cells, that gene is suppressed, deactivated. The researchers, from Geron Corporation and the University of Texas Southwest Medical Center, inserted an activated telomerase gene into the cells. The fact that normal cells possess the telomerase gene but do not employ it may be a warning signal. Activate that gene and the cell may start runaway cancerous growth. Without causing cancer.