FGF2 and atrial fibrillation: To observe the function of miR-194 and FGF2 in vivo, WT B6 mice were inoculated i.v. with 4 nM miR-194 agonism plus 25 μg FGF2 recombinant protein 12 h prior to, as well as 1 and 3 days after AF or virus (103 TCID50 of A/Beijing/501/2009) instillation.