As expected, the Western Blot analysis results showed that high-dose doxorubicin specifically increased the expression levels of phosphorylated AMPK (p-AMPK), p-ULK1 (555) and p-ULK1 (757) to activate AMPK-ULK1 signal pathway in DR-BC cells, however, high-dose doxorubicin did not influence AMPK-ULK1 activation in DS-BC cells (Fig. 4a, b), which enlightened us that AMPK-ULK1 signal pathway might be crucial for high-dose doxorubicin induced autophagy in DR-BC cells. Here, ULK1 is linked to breast cancer.