Define metastasis and viral oncogenes.

(N/A) Metastasis: The property of malignant tumors where cells slough off from the tumor and reach distant sites through the blood to form new tumors elsewhere is called metastasis. This is the most feared property of malignant tumors.
Viral Oncogenes: Cancer-causing viruses are called oncogenic viruses,and their genes are known as viral oncogenes. In normal cells,these genes are present as proto-oncogenes,which,upon activation under certain conditions,lead to oncogenic transformation of the cells.