ERBB2 and breast carcinoma: To investigate the potential clinical relevance of our findings, we performed an exploratory analysis of breast cancer patient specimens (Table 1, Figure 6A) and found that ATG4B positivity was observed in a higher fraction of HER2 positive specimens as compared to HER2 negative samples (21% vs. 6% ATG4B positive, respectively; p=0.0204; Table 2).