Scientists find another piece in the jigsaw puzzle to help explain why most plants do not develop cancer spontaneously Cancer cells proliferate uncontrolled, so regulation of the entry into the cell division cycle by external hormonal and stress stimuli is a central theme of cancer research. In contrast to animals, plants appear to have strong preventive mechanisms to avoid this kind of uncontrolled cell division. On the other hand, and unlike animal cells, plant cells that fulfill specific functions and are therefore differentiated are able to reactivate cell division. This is the reason why it is possible to regenerate new plants from individual cells in tissue culture. However, because of the differences between plants and animals, the identification of functions regulating the plant cell cycle may provide an important lesson about how evolutionary changes have led to less rigorous control of cell proliferation in mammals.
Plants harbour several different CDKs that are all related to their yeast and animal counterpart.
Two major types of CAKs have so far been identified. These CAKs, known from animals and fission yeasts, make contact to a particular part of a subunit of the RNA polymerase II complex. The activity of this part of the subunit plays a role in the regulation of the interaction of the RNA polymerase with proteins that regulate transcription. This phosphorylation is necessary for cell proliferation. CAKs thus seem to perform important functions throughout the life of a cell since they appear to be implicated in the control of both the cell cycle and transcription, as well as DNA repair, where they perform a distinct function, controlling carcinogenesis.