circ_VANGL1 knockdown inhibited tumor growth and enhanced doxorubicin sensitivity in vivo. T24 and J82 cells stably transfected with sh-circ or T24 and J82 cells were subcutaneously injected into the forelimb axils of nude mice, followed by the injection of doxorubicin (3 mg/kg) every 3 days. Fifteen days upon injection, the mice were killed to remove the tumor tissues. (a) Tumor volume was detected every 3 days for 15 days. (b) Tumor weight was measured. (c) The expressions of circ_VANGL1, miR-145-5p, and SOX4 in xenograft tissues were determined by RT-qPCR. (d) Proliferation in xenograft tumors was assessed by Ki67 Immunohistochemistry. (e) The protein levels of SOX4, c-casepase-3, and ki-67 were assessed by western blot. *P < 0.05.