If so, ethambutol hydrochloride in the blood would seem to have an even greater protective effect on cancer cells, because they would have no mechanism to make copies or suppress their activity. The discovery, then, that telomerase activity is regulated by telomeres is a significant step forward. But there are still serious limitations that still make it impossible to fully understand the function of telomeres. First, the mechanism of telomerase regulation has not yet been described. Although this is the first time that an enzyme is known to regulate and control the activity of telomerase, it is not yet clear how this could be done and whether it is possible for telomerase to be turned off. Another important limitation is that no direct relationship has been established between telomerase activity and telomere length. The fact that telomerase is not expressed in most cells or that telomeres are not preserved after telomerase is turned off seems to imply that it is not the cell's telomeres that are regulated; rather, the cell's overall health might be improved, and possibly lengthened, if telomeres were intact.
Another ethambutol hydrochloride is that telomerase inhibitors do not block telomere replication, but rather cause telomeres to degrade, so it might be possible that telomerase would be useful even in cells that lack telomerase to maintain the activity of a cell's telomerase. There is also a question of the role of endogenous telomerase. Because telomerase does not regulate telomere length, its regulation is unlikely to be responsible for aging and senescence.
However, there is evidence that some individuals and animals have reduced telomerase activity even in their adult years. The question is, then, how might telomerase work if it is a normal part of cellular function, and if it is also involved in aging and other age-related processes. This question was addressed in a study published in 2002 by scientists from the Max Planck Institute for Biology in Darmstadt. The telomerase activity of the human telomerase protein.