PERSISTENT INHIBITION OF DNA-SYNTHESIS AFTER RADIATION EXPOSURE IN 4 CLONES OBTAINED FROM RAT EMBRYO FIBROBLASTS BY TRANSFECTION WITH THE ONCOGENES H-RAS PLUS V-MYC

We have previously shown that two cell lines, 2.8 and 3.7, obtained fr om rat embryo fibroblasts (REF) by transfection with the oncogenes, H- ras plus v-myc, experience a prolonged inhibition of DNA replication a fter exposure to ionizing radiation as compared with normal REF, or RE F expressing, H-ras or v-myc alone. We report here that four additiona l cell lines generated in our laboratory by cotransfection of REF with the -same oncogenes also show prolonged inhibition of DNA replication after radiation exposure. These results indicate a regulatory mechani sm for DNA replication in irradiated REF in which the products of the oncogenes H-ras and v-myc have a central role.