Question

p53 in the Cell Cycle...

Answer 1

is a protein that functions to block the cell cycle if the DNA is damaged. If the damage is severe this protein can cause apoptosis (cell death).

p53 levels are increased in damaged cells. This allows time to repair DNA by blocking the cell cycle.
A p53 mutation is the most frequent mutation leading to cancer. An extreme case of this is Li Fraumeni syndrome, where a genetic a defect in p53 leads to a high frequency of cancer in affected individuals.

Answer 2

p53 is known as tumor suppersor gene coz of the above mentioned reasons by the tim

Answer 3

lack of nucleotide, UV radiation, ionizing radiation, oncogene signaling and hypoxia induce P53 expression, then P53 proteins cause cell cycle arrest, DNA repair, block of angiogenesis and apoptosis, so it is needed to block unregulated cell proliferation