This might be a very stupid question. Can you explain the mechanism by which Normal HEK293 cells become immortalized after being transfected with Sheared Ad type 5 DNA?
From what I understand, Sheared Ad 5 is responsible for suppressing the activities of the pRB/p53pathways, which control cell growth. That's why the cells can just keep on growing without any sort of regulatory inhibition. They're useful for the production of proteins because of how easy they are to transfect (https://altogen.com/product/hek-293-transfection-reagent-epithelial-kidney-cells/) and the 293T cell line (with the SV40 antigen) is even more useful for the production of retroviral vectors.
In addition to Matt, Adenovirus genes responsible for immortalisation of HK293 should be E1A and E1B, whose gene products inhibit RB and p53 pathways, respectively.
However, I don't know if actual contribution of these gene products has been experimentally confirmed. It will be appreciated if somebody could point out the actual works.