The lack of FAK activation observed in CTS stimulated degenerate AF cells suggests involvement of alternative mechano-receptors and it would therefore be of interest to investigate the involvement of other non-RGD recognising receptors (e.g. the collagen receptors α1β1 and α2β1 integrins (see review by Loeser [37]), and the hyaluronan receptor CD44 [50]) in AF cells derived from degenerate IVDs. The gene discussed is PTK2; the disease is atrial fibrillation.