The purpose of this project is to find differences between metastatic and non-metastatic tumors which can be exploited with chemotherapeutic or other methods. The system under study is the transplantable B16 mose melanoma. Cell lines have been isolated from this tumor having various metastatic properties. The growth requirements of these cell lines in tissue culture are being investigated with the anticipation that difference in metastatic behavior will be correlated with differences in growth requirements.