To investigate the role of ADAM9 in ESCC progression, ADAM9 knockdown cells were generated using lentiviral shRNAs targeting different regions of ADAM9. No obvious change in cell proliferation rate was detected in control versus ADAM9 knockdown cells by MTT assays over a period of 3 days (Figure S2A-B). Here, ADAM9 is linked to esophageal squamous cell carcinoma.