(A) circFMN2 knockdown inhibits tumor growth in vivo. (B) The tumor volume curve of nude mice was analyzed. (C) The tumor weights of nude mice were measured. (D) IHC analysis was performed to examine the expression levels of proliferation marker Ki-67 in tumors of nude mice. Knockdown of circFMN2 significantly decreased the percentage of Ki-67 positive cells in tumors of nude mice compared with that of sh-NC xenografts. **P<0.01.