To determine whether TGF-β signalling and breast cancer metastasis could be ablated by UCHL1 inhibition, Liu et al. used a covalent irreversible inhibitor 6RK73 (CAS number: 1895050-66-4), identified in a recent patent filed by Mission Therapeutics (Fig. 2a) [64, 65]. The gene discussed is UCHL1; the disease is breast cancer.