However, proximal tumours developed in a p53-independent manner which may indicate a preference towards the mutator phenotype
with the accumulation of mutations owing to mismatch repair deficiency.
This finding, termed microsatellite mutator phenotype
or microsatellite instability (MSI), is detectable in more than 90% of colorectal cancer specimens from patients with HNPCC and in 10% to 15% of sporadic colorectal cancer specimens.
Transient expression of a mutator phenotype
in cancer cells.
On the other hand, in Mi smegmatis, the abrogation of the Ung activity leads not only to increased mutator phenotype
but also to growth inhibition by reactive nitrogen intermediates (7).
Studies of hereditary tumors of the colorectum have identified 2 major pathways by which CRCs develop--the suppressor gene pathway and the mutator phenotype pathway.
In the mutator phenotype pathway, enzymes that normally act to repair inaccurately copied DNA no longer function or function only partially.
Although the suppressor gene pathway and the mutator phenotype pathway can be described as part of the early development of some CRCs, much less effort has been devoted to describing molecular changes related to invasion and metastasis of CRCs.
Therefore, a mutation Gly to Arg at position 58 may have a important effect on enzyme activity and lead to a mutator phenotype.
tuberculosis in genes that might result in a mutator phenotype and therefore a plausibly better adaptation of the bacilli to a hostile environment (34).
One strain carries the mutation 37 in ogt but no mutation in mutT4, a reversion that might have occurred after a transient mutator phenotype.
Recent studies provided evidence for a role of mutator phenotypes in the emergence of MDR clinical Pseudomonas isolates (16).
The failure to show mutator phenotypes
in Beijing/W strains suggests that this role may have been transient (10,11).