A laminin B2 chain cDNA clone was isolated from a human lung cDNA library by screening with antibody against mouse laminin. The authenticity of the human cDNA clone was established by comparison of the nucleotide and deduced amino acid sequences of the cDNA insert with those of the previously reported mouse laminin cDNA clones. The human clone (LC7) contained an insert of 0.75 kb (kilobase pair) that corresponded to the last 232 amino acid residues in the carboxyl terminus of the B2 chain. Northern blot analyses with the LC7 probe detected two mRNA transcripts of 8.2 and 5.6 kb in both normal human skin fibroblasts and three human tumor cell lines. The cDNA probe was also used in Southern blot analysis of DNA from human rodent somatic cell hybrids to localize the gene to human chromosome 1. In situ hybridization of the cDNA with metaphase chromosome spreads confirmed the assignment and further mapped the human laminin B2 chain gene to the long arm of chromosome 1 in the band q31.