CPF, also known as nuclear receptor subfamily 5 group A member 2, orphan nuclear receptor NR5A2, HB1F, fetoprotein transcription factor, FTF, CYP7A promoter binding factor, and LRH1 is a 54 kD nuclear receptor protein. CPF is a member of the FTZ-F1 sub-family and is highly expressed in the pancreas and to a lesser extent in the liver. CPF contains a DNA binding domain, a hormone ligand-binding domain, and two zinc finger domains and binds to DNA as a monomer. CPF is known to regulate transcription of the liver enzyme cholesterol 7-alpha-hydrolase that converts cholesterol to bile acids and to activate the hepatitis B virus enhancer II to contribute to the liver-specific expression of this virus. CPF interacts with multiprotein bridging actor 1 and the orphan nuclear receptor SHP and has been suggested to regulate pancreas-specific gene expression and play a role in embryonic development. There are at least 3 alternatively spliced isoforms of CPF; isoforms 1 and 2 are present in fetal and adult liver and in liver cancer cells such as HepG2. The Poly6066 recognizes human CPF (amino acids 1-67) and has been shown to be useful for Western blotting.