“…In particular, in PDL cells, Postn, which is among the extracellular matrix adhesion molecules mainly expressed in the bone, periosteum, and PDL tissues (KruzynskaFrejtag et al, 2004;Ma et al, 2011;Rios et al, 2005), was significantly decreased in the M1 PDL in 10-week-old Mkx −/− mice in vivo. In addition, Postn-deficient mice exhibit a phenotype of vertical PDL expansion and alveolar bone resorption in the M1 furcation area (Horiuchi et al, 1999;Rios et al, 2008), suggesting that PDL phenotype in Mkx −/− mice could, in part, be due to the suppression of Postn. If PDL width is expanded because of the absence of Postn and consequently loses its physical strength, it is possible that PDL has a compensating mechanism, and it changes to an osteogenic phenotype.…”