This series of animations shows how mutations in the p53 gene are found in 70% of lung tumors, the highest rate for any cancer.

P53 Mutations in the p53 gene are found in 70% of lung tumors, the highest rate for any cancer. The p53 protein is a tumor suppressor, analogous to car brakes, because its activity helps counter tumor development. P53 occupies a "checkpoint" in the cycle of cell division, where it "senses" DNA damage or mutations. The cell cycle is composed of four stages: During the first Gap Phase (G1) the cell grows and replenishes its resources. During S Phase (S) the cell synthesizes DNA in preparation for cell division. During the second Gap Phase (G2) the cell synthesizes proteins and other cellular components needed for cell division. During Mitosis Phase (M) the cell divides into two daughter cells. P53 acts as a checkpoint into the critical Synthesis (S) and Mitosis (M) Phases. After receiving information from DNA repair systems, p53 can signal the cell to stop dividing, allowing time for a mutation to be repaired before it is passed on to daughter cells. For example, p53 arrests the cell cycle, allowing time to repair G-T mutations induced by benzo[a]pyrene. If the DNA damage is too great to repair, p53 can signal the cell to commit suicide by the process called apoptosis, or programmed cell death. Mutations in p53 cause a loss of checkpoint control, allowing mutations and DNA damage to accumulate in a cell lineage.

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