To explore the role of TGFβR1-Smad2/3 pathway in ESCC sphere cells, we added SB431542 to the culture system, CCK-8 result showed that the survival rate of ESCC sphere cells decreased significantly following the addition of SB431542 (Fig. 5F). This evidence concerns the gene TGFBR1 and esophageal squamous cell carcinoma.