Elevated telomerase activity in cancer cells leads to the immortality of the cells, allowing for continual proliferation. A normal cell has a defined number of replication events (mitotic divisions) that it is able to undergo - the Hayflick limit. This prevents any mutant cells from proliferating continually, through the shortening of telomeres and eventually resulting in the induction of apoptosis. Due to this mechanism being mutated in cancerous cells, the cell is able to replicate indefinitely. This is beneficial in cell lines, which are typically derived from cancer tissue samples, however is not a good thing when occurring in a living organism. Due to telomerase activity being elevated, it is possible for the telomeres to be extended through the cell’s lifecycle, preventing the erosion of genetic material. Elevated telomerase activity can be beneficial in reducing the effects of aging, however if the activity is too high a tumour may form.