Are oncogenes involved in invasion and metastasis?

In carcinogenesis, the acquisition of invasiveness and metastatic capability are the key steps towards malignancy. Clinical and experimental data suggest that invasion and metastasis necessitate cellular functions other than growth and by implication the activation of separate cellular genes. We review here data about the rôle of known oncogenes in the acquisition of invasive and metastatic capabilities. Major importance is paid to the question whether actual techniques for DNA-transfection, selection, and testing of invasion and metastasis are valid for the study of the rôle of oncogenes in invasion and metastasis. We conclude that, so far, such a rôle of oncogenes is uncertain, because the majority of cell populations used as recipients in transfection experiments are able to acquire invasiveness and metastatic capability in an apparently spontaneous manner.