SMAD2 and atrial fibrillation: A correlation analysis of the SMAD2/3 signal in HEK293 cells compared to the concentration of the sol-BG in the ascites fluid that was used to treat HEK293s showed a negative correlation between sol-BG in the patient AF and SMAD2/3 phosphorylation in HEK293 cells (r = -0.7952) (Fig. 6G).