Traditional chemotherapeutic agents are cytotoxic by means of interfering with cell division (mitosis) but cancer cells vary widely in their susceptibility to these agents. To a large extent, chemotherapy can be thought of as a way to damage or stress cells, which may then lead to cell death if apoptosis is initiated. Many of the side effects of chemotherapy can be traced to damage to normal cells that divide rapidly and are thus sensitive to anti-mitotic drugs: cells in the bone marrow, digestive tract and hair follicles. This results in the most common side-effects of chemotherapy: myelosuppression (decreased production of blood cells, hence also immunosuppression), mucositis, and alopecia. Because of the effect on immune cells, chemotherapy drugs often find use in a host of diseases that result from harmful overactivity of the immune system against self. These include rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, vasculitis and many others.