Endoparasitic sedentary nematodes infecting plant roots are an important problem of modern agriculture. In a compatible interaction with their hosts, cyst nematodes use stylet for mechanical root penetration. The specialized nematode oesophageal glands produce and secrete proteins that facilitate the migration within the root and change morphogenetic program of plant cells. The changes in selected initial cell involve cell cycle reactivation, cell wall modification and boosting of plant primary and secondary metabolism.

Formation of cells with a duplicated genome may be a consequence of endomitosis, incomplete mitosis or endoreduplication. During endoreduplication, nuclear DNA is replicated without entering mitosis. In mammals it gives rise to trophoblast cells with extra copies of the genomic DNA, but in the animal world endoreduplication is the most widespread in insects. Multiple rounds of endoreduplication cycles produce cells with nuclei with 8C, 16C, 32C (etc.) DNA contents. To make it happen, cells must escape the mechanisms that prevent another round of replication.

The cell cycle is regulated by the activity of cyclin dependent kinases (CDKs) associated with cyclins. Their activity is opposed by various CDK inhibitory proteins. Disregulation of the cell cycle occurs in various pathological conditions - the most important of them being cancer. Therefore, there is a continuous effort to search for chemical CDK inhibitors, which may be used as antiproliferative drugs. Various compounds have been already isolated and synthesized (e.g. olomoucin, roscovitine, flavopiridol and indirrubin). All known CDK inhibitors compete with ATP in the binding with CDKs.

In the article a short description is given of genes involved in the development of neoplasia including tumour suppressors and oncogenes as well as the minimal number of changes required to transform a normal cell into a neoplastic one. Changes detected in mitochondrial DNA in solid tumours are also mentioned.