Through large-scale sequencing of clones randomly selected from libraries of human cDNAs, we have isolated a novel human gene encoding a product with 59.6% identity in amino acid sequence to human MTA1, a protein associated with tumor invasion and metastasis. This cDNA, named MTA1-L1 (MTA1 like 1), consists of 2736 nucleotides with an open reading frame encoding 668 amino acids. A single 3.0-kb transcript of MTA1-L1 was expressed ubiquitously on Northern blots. Structural analysis of the MTA1-L1 gene revealed 18 exons spanning 8.1 kb of genomic DNA. We assigned the MTA1-L1 locus to chromosomal band 11q12-13.1 by fluorescence in situ hybridization.