In several types of cancer, including breast cancer, non-small-cell lung cancer, and prostate cancer, HSP90 is overexpressed and may contribute to tumour cell survival by mediating the maturation and stability of a variety of client proteins, including the IGF1 receptor and elements of the PI3/Akt, signal transducer and activator of transcription 3 and mitogen-activated protein kinase signalling pathways (15,16). Here, STAT3 is linked to breast cancer.