SMAD4 and gastric cancer: Previous study has revealed that hsa_circ_0004872 was dramatically downregulated in gastric cancer tissues and increased hsa_circ_0004872 expression inhibited the proliferation, invasion and migration of GC cells via miR-224/Smad4/ADAR1 pathway.16 In this study, we examined the expression pattern of hsa_circ_0004872 and elucidated its biological function in the development of OS.