A method for monitoring cancer cell migration, invasion, metastasis, and the degree of metastasis, comprising the following step:
- 1) culturing cancer cells in a culture vessel in a three-dimensional environment surrounded by extracellular matrix;
- and
- 2) measuring the changes in the shape of cancer cells cultured in step 1), and the activity, expression, and changes in expression sites of the proteins associated with invadopodia formation/degradation, migration, invasion, and metastasis, and the degradation of extracellular matrix.