The initials bcl-2 stands for B cell leukaemia 2. 

Our bodies are made up of countless millions of cells.  These cells are constantly dying off and being replaced by new cells.  Some of the cells which die off do so because they are old and worn out, others have become injured or damaged, and are no longer working properly.  But, as one way of keeping the right balance between old and new cells, the body can also send signals to perfectly healthy cells causing them to self-destruct and die. This process is called apoptosis, or programmed cell death.  

The bcl-2 gene makes a very important protein which works with other substances to stop apoptosis.  There are also other proteins in the body which work to start apoptosis.  Normally these various substances are in balance, so that just the right number of cells are killed off.

The amount of bcl-2 is increased in some types of lymphoma cells. In follicular lymphoma, a genetic change - the t(14;18) - switches on bcl-2 production to very high levels. This makes the affected lymphoma cells immortal - they no longer respond to the self-destruct signals that would kill other normal cells. Increases in Bcl-2 on their own are not enough to cause the cancer, but they contribute to the survival of the cancerous cells in the body. New treatments are currently working on switching off bcl-2 and allowing the lymphoma cells to enter apoptosis and be killed off naturally by the body.