The mechanism of action of auromomycin, a new tumor-inhibitory antibiotic, was studied in a growing culture of mouse lymphoblastoma L5178Y cells and with isolated viral DNA. Auromomycin prevented growth of L5178Y cells completely and irreversibly at antibiotic concentrations higher than 0.03 microgram/ml. DNA synthesis was preferentially inhibited by the antibiotic, whereas RNA and protein synt...