Transfection of plasmids
To establish the link between anti-cancer effects of GC and involvement of STAT3 signaling pathway, A549 cells were transfected with STAT3-C Flag pRc/CMV containing plasmid DNA. Cells (5 × 104cells/well) were transfected with STAT3C DNA (300 ng/well) in serum-free media for 48 h by iN-fect™ transfection Reagent. After 48 h, cells were washed with 1× PBS and treated with GGC (30 µM) in complete media for 24 h.