Induction of the mitogen-activated p70 S6 kinase by adenovirus E1A.

Adenovirus E1A proteins can transform primary cells in culture in conjunction with other oncogenes, such as E1B or activated ras. The modulation of various cell cycle regulators by E1A is thought to be involved in this transformation process. In this paper we show that E1A enhances the expression of the mitogen-inducible p70 S6 kinase (p70s6k), a kinase which is essential for G1 progression. p70s6k mRNA and protein levels are enhanced 3-4-fold in various E1A-expressing cell lines. Similarly, the activity of p70s6k is enhanced in E1A-expressing cells in a manner partially independent of enhanced expression of p70s6k. The induction of p70s6k correlates with the presence of conserved region 1 (CR1) of E1A and with morphological transformation by E1A. These results suggest that induction of p70s6k by E1A might be involved in transformation by E1A.