ESR1 and neoplasm: Of note, IKKε, along with the JAK/STAT pathway, has been reported to regulate a cytokine network promoting cellular proliferation in a subset of triple‐negative breast tumours (Barbie et al, 2014), and PSAT1 overexpression is also a feature of a small fraction of ER+ tumours along with the JAK‐STAT pathway (De Marchi et al, 2017).