Damage to the Bcl-2 gene has been identified as a cause of a number of cancers, including melanoma, breast, prostate, chronic lymphocytic leukemia, and lung cancer, and a possible cause of schizophrenia and autoimmunity. It is also a cause of resistance to cancer treatments. Antibodies to Bcl-2 can be used with immunohistochemistry to identify cells containing the antigen. In healthy tissue, these antibodies will react with B-cells in the mantle zone, as well as some T-cells. However, there is a considerable increase in positive cells in follicular lymphoma, as well as many other forms of cancer. In some cases, the presence or absence of Bcl-2 staining in biopsies may be significant for the patient's prognosis or likelihood of relapse.