Tumor-suppressive activity of N03 gene product in v-src-transformed rat 3Y1 fibroblasts.

The expression of the N03 gene was significantly reduced in a variety of transformed cells, compared with that in parental rat 3Y1 fibroblasts. To understand the possible role(s) of its product, we have obtained transfectants expressing N03 gene from v-src-transformed 3Y1 cells. Two clones, which overexpressed N03 mRNA, showed a flatter phenotype, a reduced rate of growth, and a decreased ability to grow in soft agar. One of the clones which maintained N03 expression was completely suppressed in forming tumors in nude mice. These data suggest that the N03 gene product may have a suppressive ability on transformed phenotypes.