ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics; Breast Neoplasms/genetics; Doxorubicin/metabolism; Doxorubicin/pharmacology; Drug Resistance, Neoplasm/drug effects; Gene Expression Regulation, Neoplastic/drug effects; HSP27 Heat-Shock Proteins/metabolism; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism; Breast Neoplasms/pathology; Cell Death/drug effects; Cell Line, Tumor; DNA-Binding Proteins/antagonists & inhibitors; DNA-Binding Proteins/metabolism; Drug Resistance, Neoplasm/genetics; Enzyme Activation/drug effects; Female; HSP27 Heat-Shock Proteins/deficiency; Heat Shock Transcription Factors; Heat-Shock Proteins; Humans; Intracellular Space/drug effects; Intracellular Space/metabolism; Mitogen-Activated Protein Kinases/metabolism; Models, Biological; Molecular Chaperones; Mutant Proteins/metabolism; NF-kappa B/metabolism; Phosphorylation/drug effects; Signal Transduction/drug effects; Transcription Factors/antagonists & inhibitors; Transcription Factors/metabolism; Tumor Suppressor Protein p53/metabolism