複選題2. Which of the following statements regarding "Cancer Genetics" are CORRECT? (A) Hereditary tumors usually possess loss-of-heterozygosity in proto-oncogenes (B) All the cells in a female tumor have the same inactive X chromosome, which is because that all the tumor cells are derived from a single progenitor cell (C) A gain of function mutation in Rb will bypass the restriction point controls (D) Micro-RNAs are a new class of oncogenic factors because they function to induce errors during DNA replication (E) Some viruses can via integrating into the human genome to activate the cellular proto-oncogenes and contribute to tumor formation.