Fig. 1.

Differences between normal and cancer cells. Normal cells arise from stem cells that differentiate to specific cell types that carry out specific functions. Cancer cells lose the division limitation owing to various reasons (e.g., nDNA or mtDNA mutations or damage) and lose the ability to differentiate into specific cell types, as well as being unable to carry out specific physiological functions. During the evolution of a cancer, several mutations in genomes can occur and accumulate. Each factor increases the possibility of occurrence of mutations, insertions, deletions, or epigenetic effects that are linked to a cancer. Adapted from the National Cancer Institute (www.cancer.gov).