 During the process of tumorogenesis, it is known that diploid cells acquire mutations in genes responsible for maintaining genome integrity ("caretaker genes"), as well as in genes that are directly controlling cellular proliferation ("gatekeeper genes").Genetic instability can originate due to deficiencies in DNA repair, or due to loss or gain of chromosomes, or due to large scale chromosomal reorganizations.Losing genetic stability will favour tumor development, because it favours the generation of mutants that can be selected by the environment.