HBV does not require cell death in order to produce infectious offspring. As a result, whether HBV sensitizes hepatocytes to apoptosis for viral propagation in the liver remains debatable (18,19). It is known that HBx can inhibit apoptosis by interacting with various proteins involved in the induction of apoptosis (20-22). It has also been shown that HBV can induce apoptosis of hepatocytes in vitro and in vivo. Apoptosis is usually defined as an active process used by organisms to delete damaged or unwanted cells. Apoptosis occurs during normal development processes such as fetal loss or immune system regulation. It also occurs in response to stress signals from within or without the body. Healthy mature cells cannot divide and replace themselves; instead they undergo programmed cell death or apoptosis. Cells that are no longer needed or function abnormally will eventually be cleared by macrophages or other immune cells. Impairment of this process leads to the accumulation of unneeded cells that may cause cancer. There are two main types of apoptosis: programmed and non-programmed. Programmed cell death involves orders from within the cell itself to commit suicide. This type of apoptosis is important for removing unhealthy or unnecessary cells that could otherwise cause cancer.