POSTN and neoplasm: To determine the effects of circ‐POSTN knockdown on tumor growth and radiosensitivity in vivo, sh‐circ‐POSTN or sh‐NC‐transfected KYSE410 cells were subcutaneously injected into nude mice, followed by irradiation with or without 6 Gy x‐ray every 4 days after injection for 7 days.