Cytoglobin is the protein product of CYGB, a human and mammalian gene.
Cytoglobin is a globin molecule ubiquitously expressed in all tissues and most notably utilized in marine mammals. It was discovered in 2001 in hepatic stellate cells during liver fibrosis. Thus, it was originally called "stellate cell activated protein" or STAP. It received its current name in 2002. It is thought to help in the distribution and storage of oxygen as well as protect against hypoxia by scavenging reactive oxygen species . The predicted function of cytoglobin is the facilitation of oxygen among tissues that don't express myoglobin.