Downregulation of miR-21 expression increases PDCD4 expression in vivo. (A) Images of tumors from the nude mouse models in the NC, miR-21 mimic and miR-21 inhibitor groups. (B) The weight of tumors in the miR-21 mimic group was significantly increased compared with the NC group, and the weight of tumors in the miR-21 inhibitor group was significantly decreased compared with the NC group. Western blotting for PDCD4 (C) image and (D) densitometric analysis relative to GAPDH. (E) Relative expression of miR-21 determined by stem-loop RT-qPCR. (F) Relative expression of PDCD4 as determined by RT-qPCR. Student's t-test was used for comparisons of two independent groups. *P<0.05 vs. the NC group. miR, microRNA; NC, negative control; PDCD4, programmed cell death 4; RT-qPCR, reverse transcription-quantitative polymerase chain reaction.