Explain how a mutation can cause cancer.

Proto-oncogenes and the tumour suppressor genes are the two different genes that control cell division. A mutation in the tumour suppressor gene can cause it to deactivate because tumour suppressor genes encode proteins that supress cell division. The mutation prevents the protein from being produced causing cells to divide uncontrollably forming a tumour. A proto-oncogene stimulates the cell to divide. A mutation can cause it to become over active resulting in uncontrolled cell division and therefore, a tumour is formed. Tumour formation is enhanced when mutations occur in the tumour supressor genes and proto-oncogenes simultaneously, where there is hyperactivation of cell division and no suppression of this.