Boronic Acids/pharmacology; Breast Neoplasms/drug therapy; Breast Neoplasms/enzymology; Cysteine Endopeptidases/drug effects; Multienzyme Complexes/drug effects; Pyrazines/pharmacology; Ubiquitin/pharmacology; Animals; Boronic Acids/therapeutic use; Bortezomib; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Cysteine Endopeptidases/physiology; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Humans; Mice; Molecular Biology; Multienzyme Complexes/physiology; NF-kappa B/drug effects; NF-kappa B/metabolism; Neoplasm Transplantation; Proteasome Endopeptidase Complex; Protein Transport/drug effects; Pyrazines/therapeutic use; Risk Factors; Sensitivity and Specificity; Survival Rate; Treatment Outcome; Ubiquitin/therapeutic use