Metastasis is the most insidious and life threatening aspect of cancers. However little is known about the molecular mechanisms of tumor metastasis. A poorly metastatic Acc-2 cell line and highly metastatic Acc-M cell line were selected as an experimental model to study on metastatic mechanisms and antimetastatic procedures. In the present study, two-dimensional gel electrophoresis and mass spectrometry are combined to approach the protein profiles associated with tumor metastasis between Acc-2 and Acc-M cell lines. Image analysis of silver stained 2-dimensional gels revealed that 12 protein spots showed significantly quantitative and qualitative variations and mass spectrometry is utilized to further identify these spots. Of the identified proteins, transketolase, Dim1p, v-Ha-ras oncogene, type I collagen pro alpha, tumor necrosis factor (ligand) superfamily member 4, and pirin etc, have shown associations with distinct aspect of tumor metastasis to some extent. The dissimilar expression patterns of these 12 spots indicate the different roles they may play involved in tumor metastasis.