ABCC6 and atrial fibrillation: Likewise, expression of MMP12, a promoter of ECM degradation and disc fibrosis (Gruber et al., 2014; Lv et al., 2016), Hdac2 and Tspan5, modulators of RANKL-induced osteoclastogenesis (Iwai et al., 2007; Dou et al., 2016) were all downregulated, suggesting changes in inflammation response genes in the AF of Abcc6−/− discs.