P53 is the guardian of genome from any alteration, its gene is called tumor suppressor gene . p53 checks any alteration in cell cycle ,and if the alteration happened p53 resolves or shares in activation proteins important in resolving , if the cell couldn't resolve the alteration p53 leads it to apoptosis . goingthe cell out of this nature cycle and continuing its resistance and proliferation makes it a tumor celland that make p53 very important study.