SDC4 and atrial fibrillation: Furthermore, the real-time PCR assay revealed that the expression of ECM molecules which are involved in cell migration, including Collagen type III, vitronectin, fibronectin, MMP1, Syndecan 2, Syndecan 4, SPP 1, and Elastin, were increased under AF-MSC-hypoCM compared to AF-MSC-norCM (Figure 3e).