Transformation of primary mouse embryo fibroblasts by SV40 parental and microRNA-negative viruses.

SV40, simian virus 40.
aReplicate plates (n = 4–6) were harvested per virus at each time point. Numbers of transformed foci per 1×105 cells infected by each virus were normalized to the value for the WT strain of each pair of viruses at 5 weeks, which was set as 100%. The overall transformation frequency was ∼0.05%.