neocentromere assays in cancer, that neocentromeres may occur at a higher frequency in mosaic Turner syndrome than observed. Epigenetic regulation As aforementioned, the formation of the centromere is well known to be regulated epigenetically. However, those epigenetic mechanisms are still debated contentiously; fortunately, neocentromeres provide a model system for studying different proposed mechanisms. Centromeric proteins Centromeres are well-associated with specific proteins that are involved in the formation of the kinetochore and the mitotic spindle. Because neocentromeres do not contain repetitive sequences, they are good candidates for studying the epigenetic regulation of distributing centromeric proteins, using chromatin immunoprecipitation (ChIP) methods. All centromeres are associated with centromere protein A (CENPA). CENPA also been widely studied as an important player in centromere regulation as it binds and specifies centromere location for both normal centromeres and neocentromeres, regardless of DNA sequence. There is a general consensus that CENPA assembles into octameric nucleosomes, with two copies of CENPA replacing two copies of histone H3 at the target locus—this is the simplest model and much is still unknown about the composition of CENPA nucleosomes. Neocentromeres have been useful tools in investigating the effects of CENPA in the absence of satellite sequences. Those studies conclude that the ability of CENPA to wrap DNA seem to be independent of DNA sequence. This leads to several questions: how does CENPA, then, decide where to wrap? What is the purpose of satellite sequences (that are present at most eukaryotic centromeres) if they are not needed for CENPA wrapping? To complicate the matter even further, introducing alpha satellite DNA into cells can cause de novo formation of centromeres. So far, this suggests that the repetitive sequences may play a fundamental but not necessary role in centromere formation. Moreover, non-repetitive centromeres have also been recently observed in horses, orangutans and chickens. Overexpression of CENPA and CENPH (centromere protein H) is also associated with colorectal cancer. It may be worth noticing that the overexpression of these centromeric proteins are also related to neocentromerization. Hence, this may serve as the start of the explanation to how neocentromeres may lead to cancer. Overexpression may be due to a loss of function in regulation of CENPA by proteolysis at inappropriate times of the cell cycle. However, this link needs to be further investigated. Histone modifications That neocentromeres and conventional centromeres do not share consistent chromatin environment should also be taken into account in questioning the epigenetic