Cells that divide uncontrollably may form a tumor, or abnormal mass of cells.
When p53 is mutated, cells divide uncontrollably.
When p53 is mutated a tumor may form.
If a tumor has formed, this gene might have mutated:

1) p53
2) SNPs
3) OCA 2
4) DNA
5) gene
6) tRNA
7) malignancy
8) TRH