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Unformatted text preview: organism. Other types
of cellular insults, such as DNA damage, also induce programmed cell
death. In the case of DNA damage, programmed cell death may eliminate
cells carrying potentially harmful mutations, including cells with mutations
that might lead to the development of cancer.
During development, programmed cell death plays a key role by eliminating unwanted cells from a variety of tissues. For example, programmed
cell death is responsible for the elimination of larval tissues during amphibian and insect metamorphosis, as well as for the elimination of tissue
between the digits during the formation of fingers and toes. Another wellcharacterized example of programmed cell death is provided by development of the mammalian nervous system. Neurons are produced in excess,
and up to 50% of developing neurons are eliminated by programmed cell
death. Those that survive are selected for having made the correct connections with their target cells, which secrete growth factors that signal cell survival by blocking the neuronal cell death...
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