Effect on the invasion of A498 and 786-O cells by miR-21 expression through PDCD4. (A) Transfection efficiency was verified by quantitative PCR after transfected with miR-21 inhibitor, PDCD4 siRNA, miRNA inhibitor NC or siRNA NC for 48 h. (B) The invasion ability was observed by Transwell assay after transfected with miR-21 inhibitor, PDCD4 siRNA, miRNA inhibitor NC and siRNA NC. (C) Number of invading cells were calculated. (D) Transfection efficiency was verified by quantitative PCR after transfected with combined miR-21 inhibitor, miR-21 mimics, PDCD4 siRNA and respective NC. (E) The invasion ability was observed by Transwell assay after transfected with combined miR-21 inhibitor, miR-21 mimics, PDCD4 siRNA and respective NC. (F) Number of invading cells were calculated. Data are presented as the mean ± standard error of the mean. *P<0.05; **P<0.01. PDCD4, programmed cell death protein 4; miRNA, microRNA; siRNA, small interfering RNA; NC, negative control.