Which of these is not true of the gene p53?
a. Mutations of both proto-oncogenes and tumor suppressor genes lead to inactivity of p53.
b. Normalty.p53 functions to stop the cell cycle and initiate repair enzymes, when necessary.
c. Normalty.p53 restores the length of telomeres.
d. Cancer cells shut down the activity ofp53, even though it may be present.