BCR and atrial fibrillation: To investigate the role of BCR/NF-κB pathway signaling in the observed effect of AF on cold stress induced lung injury, the western blotting method was applied to detect the expression of Lyn, t-Akt/p-Akt, NF-κB nuclei/NF-κB total and immune factors in the lung tissue of rats after cold stress and administration of AF (Fig. 4a).