cDNA was generated using SuperScript cDNA Kit (Invitrogen). qRT-PCR was performed in PCR System with SYBR Green (Roche Diagnostics, Burgess Hill, UK). GADPH or U6 was used as the internal reference. circSMAD2, miR-1277-5p, and MFGE8 relative expression was measured using the 2-ΔΔCt method. Primer sequences are listed in Table S1.