KLK6 and atrial fibrillation: To confirm the involvement of autophagic cell death in acquired resistance to chemotherapy under AF treatment, we inhibited autophagy using siRNA-mediated ATG5 knockdown in NCI-N87 and SNU-620 cells resulted in increased cell mortality statistically after AF treatment (Figure 7A) and verified by western blot analysis of ATG5, LC3B, p53, and KLK6 (Figure 7B).