Primary cells only undergo a pre-determined and finite number of cell divisions in culture before entering replicative senescence; a state where they can no longer divide. As a result, researchers need to frequently reinitiate and establish fresh cultures from explanted tissue - a process that is not only tedious but also a source of introducing significant varia­tion within different culture preparations. In order to have consistent material over the course of a research project, researchers need primary cells that have an ex­tended replicative capacity, or immortalized cells.

There are several methods for immortalizing mammalian cells in culture. The most researched and applied methods include (a) use of Simian Virus 40 (SV40) T antigen (b) induced expression of Telomerase Reverse Transcriptase protein (TERT) and (c) inactivation of the tumor suppressor genes (p53, Rb, and others). With many years of experience in cell immortalization, abm has developed the most comprehensive cell immortalization products that comprise ready-to-use retroviral, lentiviral and adenoviral vectors for hTERT, p53 and RB, siRNAs and SV40 T antigens.