Transduction of primary cell cultures with BMI-1 (inactivating CDKN2A/RB pathway), SV40 (binding and inactivating tumor suppressor protein TP53) and hEST2 (generally up-regulated in tumor cells and during immortalization, preventing senescence resulting from telomere shortening) was insufficient to provide infinite proliferation. Here, CDKN2A is linked to neoplasm.