Immortalization of cells using TERT has certain advantages over the methods using the SV40 large T antigen or other approaches: i) TERT can immortalize cells without transformation or tumor formation [18]; and ii) cells immortalized by TERT not only proliferate but also differentiate or undergo maturation, whereas immortalized cells using SV40 large T antigen might lead to only proliferation without differentiation or maturation. Here, TERT is linked to neoplasm.