In our current work, we studied the expression pattern heterogeneity of mTOR activity (p-mTOR, p-S6, Rictor), glycolysis (GLUT1—glucose transporter 1, LDHA, HK2—hexokinase 2, and PFKP—phosphofructokinase), glutaminolysis (ASCT2—alanine, serine, cytein-preferring transporter 2, and GLS), and other metabolic pathway markers (ATPb—β-F1-ATPase, CPT1A, FASN, ACSS2—acyl-CoA synthetase short-chain family member 2, and ACC—acetyl CoA carboxylase) by IHC in a representative BC tissue panel (n = 40, 10 from each main breast cancer subtype). This evidence concerns the gene SLC1A5 and breast cancer.