STAT3 and Pleural effusion: Interestingly, many clients or interactors of Hsp90, such as epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (ErbB2), the mammalian target of rapamycin (mTOR) and signal transducer and activator of transcription 3 (STAT3), have been implicated in the pathogenesis of ovarian cancer cells [5–7] and elevated Hsp90 level is common in peritoneal and pleural effusions of patients with advanced–stage ovarian cancer cells [8].