ROCK2 and atrial fibrillation: The expression of ROCK2 protein (normalized to GAPDH) by immunoblotting in left atrial tissues of the MR AF patients (n = 6) was significantly higher than the expression of ROCK2 of the normal control subjects (n = 3) (2.32 ± 0.18 vs. 0.53 ± 0.16, p = 0.020) (Fig. 7a).