By analysing the metabolic processes of MCL cells and their response to the Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib (IBR), Lee et al. proposed imaging biomarkers (lactate and alanine) to detect response and resistance to IBR in MCL and suggested pathways to overcome IBR resistance, most notably glutaminolysis, the major oxidative ATP-producing pathway in these cells [67]. The gene discussed is BTK; the disease is mantle cell lymphoma.