Background: Heat shock protein 70 (HSP70) is constitutively expressed in normal cells but aberrantly expressed in several types of tumor cells, helping their survival in extreme conditions. Thus, specific inhibition of HSP70 in tumor cells is a promising strategy in the treatment of cancer. HSP70 has a variety, of isoforms in the cellular organelles and form different functions by co-ordinating and cooperating with co chaperones. Cancer cells overexpress HSPs during cell growth and proliferation and HSP network provides resistance against apoptosis. The present study aimed to evaluate quantitative changes in HSPs- and cancer-associated gene expressions and their interactions in the presence of 2-phenylethyenesulfonamide (PES) in MCF-7 cells.