IRS4 and neoplasm: IRS4-positive tumours were enriched among triple-negative/basal-like (6/25, 24%) and HER2-enriched tumour subtypes (2/18, 11%), whereas virtually absent in the luminal A (1/67, 1%) and B (1/47, 2%) subtypes (P=2.68 × 10−3, Pearson's χ2-test; Fig. 6e; Supplementary Data 2).