Annexin A1 aka Lipocortin is a protein and an antibody to the ANXA1 gene family. It is normally expressed clinically in stem cells and cancer stem cells. Research studies on genetics have established that anyone who tests positive for Annexin A1 antibody must be diagnosed and treated for Hairy Cell Leukemia. This type of blood cancer is slow growing and results in excessive lymphocytes in the bone marrow. That’s why people with hairy cell leukemia have low levels of red blood cells, white blood cells and platelets. Annexin A1 test is performed during and after the treatment of Hairy Cell Leukemia.