The mechanisms controlling AQP5 expression are not very well understood, but expression of AQP5 has been correlated with methylation levels of its promoter, with a reduced expression when the promoter was highly methylated [ 11– 13].
Factors controlling dedifferentiation in newt limb are not well understood; however, expression of the muscle segment homeobox gene msx-1 is induced in the blastema [20] and also in regenerating amputated mammalian digits [21], suggesting a role in dedifferentiation.
While the physiological roles of HIC are not yet well understood, its expression, like that of its Xenopus ortholog XIC, appears to be under tight control [42], [48] (Q. Wang et al., unpublished results).
Though not well understood, the altered expression of apelin we observed in the diabetic heart in response to rosiglitazone may present a novel pathway for the study of diabetic cardiomyopathy.
Despite our knowledge of the regulatory mechanisms affecting transcription, it is not well understood how the expression levels of transcripts correspond to downstream protein abundances.
Down-regulation of claudins in cancer seems to be well understood, but increased expression of claudin contributing to neoplastic progression is less clear [ 1].
Because the role of VEGF189 and VEGF206 in vivo is not well understood and their expression is low compared to VEGF121 and VEGF165 [ 3], we consider the two main isoforms VEGF121 and VEGF165 in our model.
Yet it is not well understood how left/right gene expression patterns are regulated.
Although the regulation of VEGF expression is becoming well understood, its mode of action, particularly the regulation of expression and distribution of the three primary isoform (VEGF121, VEGF165 and VEGF189), remains unclear.
Although the role of DNA methylation in the control of imprinted expression is relatively well understood, advances in the understanding of other factors regulating imprinted expression have been made more slowly.
