This difference in CTS-stimulated gene expression between AF cells of non-degenerate and degenerate origin illustrates a difference in the mechano-response and appears not to be due to a difference in response time as there was no change in type I collagen or ADAMTS -4 gene expression in non-degenerate or degenerate AF cells respectively, at any of the time points analysed. This evidence concerns the gene TTR and atrial fibrillation.