A cell has an inactivating mutation in one of its two p53 alleles. If this cell sustains DNA damage (e. g., to the HER2 gene), what is likely to happen?

Answer: Cell apoptosis (cell death)

Explanation: p53 protein determines whether the DNA of a cell will be repaired or damaged when the DNA is affected by harmful agents (e. g. Radiation, toxic chemicals). If the DNA cannot be repaired the protein prevents the cell from dividing and signals the cell to undergo cell death, by this apoptosis of the cell, this stops the cell from undergoing mutation or division which then prevents the development of tumours.