HMGB1 and atrial fibrillation: Compared with well‐established LC3‐II and p62/SQSTM1 to monitor autophagy,40 time‐dependent changes in the expression and localization of HMGB1 observed by independent nuclear and cytoplasmic HMGB1 measurements is noteworthy, suggesting the usefulness of HMGB1 as an autophagy sensor in adult disc AF cells, similar to embryonic fibroblasts and cancer cells.41 Western blotting for total (nuclear + cytoplasmic) HMGB1 expression supported stress‐reactive cytoplasmic translocation, followed by extracellular release, of HMGB1 nuclear protein.