Breast cancer is ranked as the second highest cause of cancer death in women of all ages, preceded only by lung cancer. The most prominent difference between tumors and normal cells is their proliferative capacity. While normal cells have a limited life span and show replicative senescence, tumor cells are immortal. The biochemical mechanism responsible for tumor cell immortalization, and conversely for normal cell senescence, involves an enzyme termed telomerase Это и многое другое вы найдете в книге Telomerase and cancer therapy with nanoparticles (Fatemeh Kazemi-Lomedasht)