Screening of antibiotics preferentially active against ras oncogene-expressed cells.

During the course of in vitro screening of agents which are preferentially active against ras oncogene-expressed cells, a new anthracycline (identified as 2-demethylsteffimycin D) and a heptaene (possibly a new member of partricins) were isolated from microbial fermentation broths. Among known compounds tested, 5-fluorouracil, 5-fluorodeoxyuridine and oxanosine showed high selectivity towards ras oncogene-expressed cells.