The Effect of the Deletion of One Copy of the Gene

The effect of the deletion of one copy of the gene encoding p53 is different from the effects caused by other p53 mutations. For example, some loss-of-function mutations in the DNA-binding domain of p53 cripple its function as a transcription regulator. Such a mutation in only one copy of the p53 gene can be enough to confer a p53 loss-of-function phenotype, even when the other copy of the gene on the homologous chromosome is wild type. This is because …

A) p53 is a proto-oncogene.
B) these mutations are recessive.
C) p53 is a tumor suppressor.
D) p53 forms a tetramer.
E) p53 can induce apoptosis.