We report the cDNA sequence and genomic structure of gly96, an immediate early gene inducible by serum growth factors in mouse fibroblasts. It encodes a 153-amino acid protein that does not share significant sequence similarity with any known protein. In the adult mouse, gly96 is expressed predominantly in the lung, testes and the uterus. We have identified the Gly96 protein in Balb/c 3T3 cells using affinity-purified antibodies recognizing the Gly96 polypeptide. We show that Gly96 is glycosylated and has a short half-life in serum stimulated fibroblasts.