Fibroblast activation protein-α: a key modulator of the microenvironment in multiple pathologies.

Fibroblast activation protein-α (FAP) is a serine protease that can provide target specificity to therapeutic agents because in adults its expression is restricted to pathologic sites, including cancer, fibrosis, arthritis, wounding, or inflammation. It is not expressed in most normal tissues. The majority of FAP is expressed by activated fibroblasts responding to the pathologic situations.

Fibroblast activation protein-α promotes tumor growth and invasion of breast cancer cells through non-enzymatic functions.

Fibroblast activation protein-α (FAP) is a cell surface, serine protease of the post-prolyl peptidase family that is expressed in human breast cancer but not in normal tissues. Previously, we showed that FAP expression increased tumor growth rates in a mouse model of human breast cancer. Here the role of the proteolytic activities of FAP in promoting tumor growth, matrix degradation and invasion was investigated.