A continuously growing cultured cell line has been obtained in vitro, starting from a specimen of ascites fluid obtained from a patient with ovarian cancer, in whom a poorly-differentiated adenocarcinoma was diagnosed. This cell line, named OC-A1, is routinely grown in standard, serum-supplemented culture medium and has been fully stabilized to long-term growth and characterized for both cultural and genetic parameters. OC-A1 cells express a set of characteristics, as determined in vitro which, when compared with the in vivo primary tumor, confirm the high malignity of this cancer. In addition, karyotype analysis showed a translocation of chromosome 8 which is correlated with the amplification of c-myc oncogene. However, the expression of this oncogene was found to be significantly inhibited by a new regulatory activity, recently found to be present in a liposarcoma cell line. Conditioned medium from these cells was indeed able to inhibit the growth of OC-A1 cells, arresting their cell cycle in the G1 phase and inducing them to apoptosis. Finally, the cell programmed death appeared to be related to the expression of antioncogene p53.