Which of the Following Statements About Cancer Is Not True

Which of the following statements about cancer is not true?

A) Cancer is very often associated with problems at the G₁ checkpoint.
B) For a tumor to be defined as "cancer," it must first metastasize.
C) Cancer cells often have a defective form of the tumor repressor p53.
D) Many cancer cells have defective forms of the signal transduction protein Ras that do not become deactivated.