SMAD2 and lung cancer: Surprisingly, curcumin reduced subcutaneous tumor growth in lung cancer cells independent of their TGF-β status, while abrogating TGF-β signaling by inhibiting TGF-β-induced Smad2 and Smad3 phosphorylation in TGF-responsive H358 and A549 cells, but not in ACC-LC-176 cells wherein TGF-β signaling was non-functional [56].