Dosage balance should also be maintained in cellular circuits and networks where there are opposing forces such as a kinase versus a phosphatase or a transcription activator versus and inhibitor. After polypolidi-zation, duplicated genes encoding interacting proteins that are dosage sensitive tend to survive together because deletion of one copy would mimic an aneuploid effect. Regulatory genes that are in balance can be preserved from non-functionalization for millions of years and this has been observed in Arabidopsis,Olaparib rice and other organisms and references therein. On the other hand, genomic analyses and experiments have provided evidence that after a WGD there is a strong tendency to go back to a diploid state, suggesting that diploidy is the most stable state. Indeed, DNA deletions due to intra/interchromosomal rearrangements and chromosome losses owing to segregation defects are concomitant with the return to a diploid state. Deletion of genes that are not necessary in multiple copies can be advantageous because their expression imposes a triple cost to the cell: futile replication, transcription and translation. However,Selumetinib such deletions might indirectly affect gene-product dosage balance and, as discussed below, in most cases they should not be massive and rapid. By virtue of the nucleotypic effect of DNA, DNA deletions in a newly formed polyploid is expected to decrease nuclear and cell volumes. Assuming that such a hypothetical volumetric contrac-tion does not alter substantially transcription levels on a per-allele basis, it would lead to an increase in the concentration of the products of genes that remain as duplicates. This might be advantageous for a subset of genes but not for all. Here, we explore the idea that proliferation of non-coding DNA compensates for DNA deletion sections). After autotetraploidization, the right balance is main-tained because expression of both M and N is increased with ploidy along with the volumetric increase. Of course, if one paralogous copy of the genes encoding either M, N or the protease is deleted, an imbalance will appear.