We demonstrated that while incubation with IL-1β or miR-21 mimics promoted the AF trait of SW982 cells as demonstrated by increased α-SMA protein expression, treatment with the miR-21 inhibitor alone or in the presence of IL-1β markedly suppressed the expression of α-SMA protein (Figure 2A,B). The gene discussed is ACTA1; the disease is atrial fibrillation.