Nevertheless, miR-1 represses GJA1 (encoding connexin 43, the gap junction α1 protein) and KCNJ2 (encoding IK1 protein Kir2.1), thus its downregulation results in increase in protein Kir 2.1 expression, a key factor in AF maintenance (209). The gene discussed is KCNJ2; the disease is atrial fibrillation.