Analysis of the SCAN-B data showed that expression of miR-21-5p and miR-21-3p were significantly higher in tumours belonging to the HER2-like subtype vs other subtypes (P = 9.56 × 10−9 and P = 1.40 × 10−7, respectively, Student’s t-test) (Fig. 3a,b) and in accordance with our results, miR-21-5p degradation ratios were also lower in the HER2-like subtype vs other subtypes (Fig. 3d) (P = 2.66 × 10−5, Student’s t-test). The gene discussed is ERBB2; the disease is neoplasm.