The metastasis-associated gene 1 (mta1) was identified initially in rat highly metastatic cancer cell lines and found to be a component of the nucleosome remodeling and histone deacetylase (NuRD) complex. The gene for mouse mta1 was screened and its genomic structure was determined. It consists of 21 exons spanning 40 kb of genomic DNA. The full-length mouse Mta1 cDNA contained a 2145 nucleotide open reading frame encoding 715 amino acids. In addition to the full-length cDNA, several alternative splicing variants were found. Some differences in the splicing variants found were observed among various mouse organs and cells examined by the semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). The cDNAs of the splicing variants were inserted into green fluorescent protein (GFP) expression vector and the subcellular localization of the GFP-Mta1 fusion proteins were analyzed. Knowledge of the Mta1 gene expression pattern will be useful in better understanding its functional diversity.