aP2 (adipocyte Protein 2) is a carrier protein for fatty acids that is primarily expressed in adipocytes and macrophages. aP2 is also called fatty acid binding protein 4 (FABP4). Blocking this protein either through genetic engineering or drugs has the possibility of treating heart disease,diabetes, asthma, obesity, and fatty liver disease.

Baxa et al. (1989) purified human adipocyte FABP (called H-ALBP by them) from normal subcutaneous adipose tissue. The 15-kD protein composed about 1% of total cytosolic protein in human adipose tissue. They also cloned a full-length cDNA that encodes a predicted 132-amino acid polypeptide. Baxa et al. (1989) also identified a consensus tyrosyl kinase phosphorylation site.