Metabolic enzyme expression heterogeneity in the studied breast cancer tissues. (a) Metabolic plasticity in tumour tissue and its importance in the overall survival of breast cancer patients. Two breast cancer cases with different metabolic plasticity at the tissue level—the Luminal B (LumB) case with high metabolic plasticity (based on Rictor, p-S6, GLS, FASN and CPT1A IHC staining and their high staining intensity) had a short overall survival of only 14 months; however, in another triple-negative breast cancer (TN) case with low metabolic plasticity, a much longer overall survival period was observed (201 months). High metabolic plasticity was considered if high mTOR activity was accompanied with intensive staining of a minimum of two studied metabolism-related enzymes. (b) Representative staining of several metabolic enzymes (Rictor, p-S6, p-mTOR, ACC—acetyl-CoA carboxylase, ASCT2—alanine, serine, cysteine-preferring transporter 2, FASN—fatty acid synthase, CPT1A—carnitine palmitoyltransferase 1A, and HK2—hexokinase 2) showed high tissue heterogeneity in the studied breast cancer cases. 3,3′-diaminobenzidine (DAB) (brown) was used as a chromogen. Scale bars are given in the figures.