HSPB1 and cancer: Consequently, drugs that interfere with the pro-reducing capability of HspB1 and HspB5 by interfering with their interaction with anti-oxidant enzymes may improve the killing efficiency of anti-cancer therapeutic drugs or conditions which depend on the intracellular redox state or the production of reactive oxygen species for their action, such as the Hsp90 inhibitor 17AAG or X-ray irradiation [196,203].