miR-30b/c targets Rab18. (A) Wild-type (WT) and mutant (Mut) of putative miR-30b and miR-30c targeting sequences in Rab18 mRNA. Mutant sequences were shown in bold type. (B) Analysis of luciferase activity. HEK293 cells were cotransfected with miR-30b or miR-30c mimics and negative control oligonucleotides, pRL-TK and firefly luciferase reporter plasmid containing putative miR-30b/c targeting sequences of Rab18. pRL-TK was cotransfected as an internal control to correct the differences in both transfection and harvest efficiencies. The firefly luciferase activity of each sample was normalized to the Renilla luciferase activity. The normalized luciferase activity control oligo nucleotides was set as relative luciferase activity 1 respectively. (C,D) Effects of miR-30b/c on the endogenous Rab18 expression levels. A549 and H23 cells were cotransfected with miR-30b or miR-30c mimics and negative control oligonucleotides. Forty-eight hours after transfection, cells were isolated, the mRNA levels (C) and protein levels (D) of Rab18 were analyzed by qRT-PCR and WB, respectively. (*P < 0.05, **P < 0.01, Student’s t-test).