[9][10] A soluble form of FAP, which lacks the intracellular and transmembrane part, is present in blood plasma.

The active site of FAP is localized in the extracellular part of the protein and contains a catalytic triad composed of Ser624 Asp702 His734 in humans and mice.

FAP is thought to be involved in the control of fibroblast growth or epithelial-mesenchymal interactions during development, tissue repair, and epithelial carcinogenesis.

[14][15] Stromal fibroblasts play an important role in the development, growth and metastasis of carcinomas.

[20] Talabostat is an inhibitor of FAP and related enzymes, for which clinical trials have been done, but further research is suspended.