The gene encompasses 35 kb of DNA; 7 exons.

1366 nucleotides mRNA; 660 bp open reading frame.

220 amino acids; 24 kDa protein. Like rat ps20, human ps20 protein contains a WAP signature domain.

Widely expressed, absent in thymus.

The rat homologue of ps20 was originally identified as a secreted growth inhibitor. These growth regulatory effects and the cell phenotypic properties in vitro, suggest that ps20 may function as a mediator of stromal-epithelial interactions and contribute to the maintenance of tissue homeostasis. The ps20 protein is assumed to function as a protease inhibitor. In vitro studies indicate that exogeneous addition of ps20 protein stimulates endothelial cell migration, and promotes angiogenesis and tumour growth in a xenograft model of prostate cancer.

The human WFDC1 protein shares approximately 86% and 88% identity with the rat and mouse proteins, respectively. WFDC1 is related to a family of human proteins that also have homology with WAP. The WFDC1 gene organization presents similarities with that of the KAL gene, which extends on 210 kb of DNA, includes 14 exons and is the largest gene in the WAP signature domain family.

Although WFDC1 was mapped to human chromosome 16q24, an area of frequent loss of heterozygosity (LOH) in prostate and hepatocellular carcinomas, no tumour-associated mutations were identified in the coding region of WFDC1 in these cancer types. Mutations in WFDC1 gene resulting in Gly9Asp, Pro211Ser and Lys217Arg substitutions have been found at low frequency in the stroma of breast carcinomas. One mutation resulting in a Pro167Ser substitution has been identified in the epithelium of breast carcinoma.