The calcium-binding protein MRP-8 is produced by human pulmonary tumor cells.

A calcium-binding protein was isolated from serum-free culture medium of human squamous carcinoma cells (HS 24). N-Terminal sequencing of the protein yielded 30 amino acids which were identical to the N-terminus of cystic fibrosis antigen. Northern blot analysis with an oligonucleotide derived from the N-terminus resulted in the detection of a transcript of approximately 600 bases. Screening of a HS 24-cDNA library with the same oligonucleotide led to the isolation of a 381-bp-cDNA encoding a protein of 93 amino acids. The corresponding protein has been identified as the calcium-binding protein MRP-8 usually found in Macrophages.