The purpose of these studies was to demonstrate causal effects of abnormalities induced in mouse chromosome 14 on tumorigenicity and metastasis using the K-1735 murine melanoma cell line. Because anomalies in chromosome 14 have previously been associated with increases in metastatic potential, we induced chromosome 14 anomalies in a nonmetastatic K-1735 clone 10 cells initially containing two normal copies of chromosome 14 by treatment with mitomycin C. Clone 10-M1, in which a small population of cells (approximately 4%) contained translocations involving chromosome 14, was isolated and injected into athymic nude mice. Unlike the parental C-10 cells, C-10 M1 cells produced experimental lung metastases. Chromosomal analysis of cell cultures established from both subcutaneous tumors and lung metastases indicated that approximately 35% of the cell population contained chromosome 14 anomalies suggesting that this chromosome may play a role in tumor growth and metastasis.