Purification and characterization of cancer suppressive factor

Cancer suppressive factor (CSF) has been purified thousandfold from the ascites of mice. The purified factor possesses an activity to kill the cancer cells in vitro but little affects the bone marrow cells. Only one protein band has been observed on the polyacrylamide gel electrophoretogram of CSF. Its molecular weight is about 4,000 daltons as estimated by ultrafiltration method.