The lysates of Ishikawa and HEC1-A cells were reacted with the magnetic bead (Millipore, Bedford, MA, USA) and anti-AGO2 (1:500, ab186733, Abcam) or control anti-IgG. Then immunoprecipitated RNA was purified, and the enrichment of circSMAD2 and miR-1277-5p were evaluated by qRT-PCR.