The p53 protein can regulate the cell in several ways: It can activate DNA repair proteins when it recognizes damaged DNA. -It can also hold the cell cycle at the G/S regulation point on DNA damage recognition. .It can initiate apoptosis,the programmed cell death,if the DNA damage proves to be irrepairable.The p53 protein can regulate the cell in several ways: •It can activate DNA repair proteins when it recognizes damaged DNA. •It can also hold the cell cycle at the G1 /S regulation point on DNA damage recognition. •It can initiate apoptosis, the programmed cell death, if the DNA damage proves to be irrepairable