The GRO gene was originally identified by subtractive hybridization studies between normal and tumorigenic Chinese hamster embryo fibroblasts. The hamster cDNA was cloned and used as a probe for cloning of the human GRO cDNA. The GROalpha gene initially cloned from T24 cells and the gene in melanoma cells encoding melanoma growth stimulating protein (MGSA) are identical. Human cells contain three closely related, but distinct GRO genes: GRO alpha, GRO beta, and GRO gamma. GRO beta and GRO