Molecular cloning and characterization of a cDNA showing tumor-suppressive activity in V-SRC-transformed 3Y1 rat fibroblasts.

Differential screening procedure was employed to isolate new genes specifically down-regulated in RSV-transformed rat 3Y1 cells (SR-3Y1) compared with parental 3Y1 cells. Among those, one clone termed N03 showed nearly complete down-regulation in v-src-, v-mos and SV40-transformed 3Y1 cells. Nucleotide sequence analysis showed that N03 protein is novel and is composed of 178 amino acid residues in length. Introduction of N03 cDNA into SR-3Y1 cells using an expression vector resulted in suppression of transformed phenotypes such as high growth rate, colony-forming ability in soft agar and tumorigenicity in nude mice.