Inhibiting the kinase activity of budding uninhibited by benzimidazoles‐1 (BUB1), as a critical mediator of TGF‐β signaling, has been found to suppress TGF‐β signaling in various normal and cancer cells as well as mice bearing lung carcinoma xenografts and to reduce the amounts of phosphorylated SMAD2 in lung carcinoma tumor tissue [263]. This evidence concerns the gene SMAD2 and cancer.