FGF4 and atrial fibrillation: Those factors not detected in either BMSC-CM or UCB ECFC derived cell-CM, but which were present in SS-AF-MSC-CM or hDF-CM included ADAMTS-1, angiopoietin-2, angiostatin, EG-VEGF, FGF-acidic, FGF-4, GM-CSF, HGF, IL-1β, IL-8, MMP-8, PD-ECGF and VEGF-C (Figures 5, 6 and Table S1).