Bax inhibitor-1 (BI-1) is an evolutionarily-conserved endoplasmic reticulum protein. The expression
of BI-1 in mammalian cells suppresses apoptosis induced by Bax, a pro-apoptotic member of the Bcl-2 family.
BI-1 has been shown to be associated with calcium (Ca2+) levels, reactive oxygen species (ROS) production,
cytosolic acidification, and autophagy as well as endoplasmic reticulum stress signaling pathways. According
to both in vitro and clinical studies, BI-1 promotes the characteristics of cancers. In other diseases, BI-1 has
also been shown to regulate insulin resistance, adipocyte differentiation, hepatic dysfunction and depression.
However, the roles of BI-1 in these disease conditions are not fully consistent among studies. Until now, the
molecular mechanisms of BI-1 have not directly explained with regard to how these conditions can be
regulated. Therefore, this review investigates the physiological role of BI-1 through molecular mechanism
studies and its application in various diseases.