The division rate of human cells is not slower than that of rat cells, indicating that the chance for DNA replication mistake in human cells is not any less than that of a rat's.
During replication of a genome, mistakes can happen.
This conundrum was largely dismissed with the simple explanation that viruses are bound to make mistakes during replication and are therefore likely to expose at least some dsRNA molecules to the cell.
The results presented here allow for bidirectional errors in replication: that is, a mistake in copying results in a variant that is one step higher or lower than the parental variant.
In addition to DNA methylation, as your article mentioned, changes also arise from other events that include mistakes during DNA replication, shifting of DNA sequences, mutations, deletions, substitutions, translocations and crossing over, and the integration of foreign DNA.
"Inevitably, mistakes in DNA replication and other mutational forces accumulate and create imperfect copies".
Modification of existing genes is primarily achieved by random mutations, which occur due to mistakes in DNA replication or mutagenic environmental conditions (Elena and Lenski 2003).
A bigger genome should induce higher probability of mistakes in DNA replication during cell division, leading to higher risk of mutation and concomitantly to cancer.
A second class of chemotherapeutics, the antimetabolites, such as aminopterin and amethopterin, do not directly interact with DNA bases but interfere with synthesis of precursors as folate and cause mistakes during DNA replication of cancer cells (Shewach and Kuchta, 2009).
But in order for oncogenic progression to occur or speed up (for transition from mod- to poor-stage liver cancer), it is logical, and indeed as we find, to target protein complexes that are involved in rectifying mistakes in DNA replication or effecting DNA repair.
