A further analysis of an additional cohort of 30 HER2-positive breast cancers (Supplementary Table 1) confirmed that miR-21 overexpression was associated with RD (p = 0.012) (Figure 1A), indicating that miR-21 is indeed involved in resistance to neoadjuvant treatment consisting of trastuzumab and chemotherapy. The gene discussed is ERBB2; the disease is breast carcinoma.