STAT3 and major depressive disorder: Kaempferol and quercetin had been reported to relieve symptoms of depression and exhibited antidepression effects through acting on interleukin-6 (IL6), mitogen-activated protein kinase 1 (MAPK1), signal transducer, and activator of transcription 3 (STAT3) and transcription factor AP-1 (JUN) [25].