The present studies clearly indicate that when expressed at high levels in H1299 cells, E4orf6 and E1B55K can mimic many of the effects of E1A on E2F; however, when these proteins are expressed at lower levels in the context of a normal viral infection, does this activity contribute in any way to the replication of wild-type virus expressing E1A? This evidence concerns the gene DHTKD1 and viral infectious disease.