STAT3 and cancer: Quercetin could increase the expression level of pro-apoptotic protein and decrease the expression level of anti-apoptotic protein13 and inhibit PI3K/AKT/mTOR and STAT3 (Signal Transducer and Activator of Transcription 3) pathways in cancer cells, thereby down-regulating the expression of survival cell proteins such as Cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (c-FLIP), cyclin D1 (cyclin-dependent kinases) and cMyc (a nuclear transcription factor)14,15.