Hepatitis B virus x interacting protein, also known as HBXIP, was originally identified by its ability to form a complex with the C-terminus of hepatitis B virus X (HBX) protein. HBXIP negatively regulates the activity of HBX and alters the replicative life cycle of the virus. In addition, HBXIP is involved in bipolar spindle formation and regulates centrosome dynamics and cytokinesis in cells, possibly through an interaction with Dynein light chain.