PECAM1 and atrial fibrillation: Colocalization of CD31 with SMA, Twist, Snail, Slug, and vimentin was significantly increased in the atrial subendocardium of patients with AF (Figure 1, B–F), and increased colocalization of CD31 with SMA and Twist was observed in the HF rabbit model (Supplemental Figure 1, B and C).