N-myc proto-oncogene expression can induce DNA replication in Balb/c 3T3 fibroblasts

N-myc and c-myc are structurally and functionally related proto-oncogenes. C-myc expression plays an essential role towards the induction of DNA replication following mitogen stimulation of quiescent cells. We have examined whether N-myc expression can stimulate cellular DNA synthesis. When growth factor-deprived quiescent Balb/c 3T3 fibroblasts harboring a glucocorticoid-inducible N-myc gene were stimulated with dexamethasone, the resultant N-myc expression induced S-phase DNA synthesis. Hence, functional homology between N-myc and c-myc extends to their joint ability to stimulate DNA replication.