   Telomerase is an enzyme that allows a cell’s DNA to maintain its length after division. Without telomerase, cells can only divide a certain amount of times before their DNA is shortened leading to cellular death. This limit of division in normal cells is known as the hayflick limit. A detailed definition of the hayflick limit can be found here.
   Telomerase is not active in normal dividing somatic cells, but has been shown to be overexpressed in cancer cells, allowing them to divide indefinitely. The firm Pharmex has developed a vaccine called GV1001, a peptide vaccine that is engineered to illicit a response to the enzyme telomerase. In theory this vaccine could be used as a universal vaccine, since cancerous cells need Telomerase to survive. It is currently being developed in numerous cancer populations.
