immortalization

Conferring on normal cells cultured in vitro the property of an infinite lifespan, as from spontaneous mutation, by exposure to chemical carcinogens, or by viral infection. I. of primary cells in culture is the first of several steps in the expression of transforming genes of DNA tumor viruses, of retrovirus oncogenes, and cellular oncogenes derived from human cancer cells.

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im·mor·tal·i·za·tion (ĭ-mor″təl-ĭ-zaґshən) acquisition of immunity to normal limitations on growth or life span, sometimes achieved by animal cells in vitro or by tumor cells; causes may be spontaneous mutation, exposure to chemical carcinogens, or viral infection.