Membrane-associated progesterone receptor component 2 (PGRMC2),also known as DG6 or PMBP,belongs to the cytochrome b5 family. This protein might play a role in cancer. The gene of PGRMC2 maps to chromosome 4q26,and encodes a 223-amino acid single-pass membrane protein with a cytochrome b5 heme-binding domain in its cytoplasmic domain. PGRMC2 has a calculated molecular weight of 24 kDa. The band of about 28 kDa detected by this monoclonal antibody is unknown but may represent phosphorylated form of PGRMC2 .