KRAS is experimentally validated as a direct target of <i>miR-126</i> in pancreatic cancer cells.

<p>(A) Putative <i>miR-126</i> binding sequences in the 3′-UTR of KRAS mRNA. Two different fragments from the 3′-UTR region of KRAS were cloned downstream of the luciferase reporters and named as wild-type (KRAS_A_WT and KRAS_B_WT). Two mutated versions of the <i>miR-126</i> binding site were also generated (KRAS_A_MUT and KRAS_B_MUT); the mutated nucleotides of the <i>miR-126</i> binding site are underlined. Boxed areas represent conserved complementary nucleotides of the <i>miR-126</i> seed sequence in various species (Hsa, human; Ptr, chimpanzee; Mml, rhesus; Mmu, mouse; Laf, elephant; Gga, chicken). *indicates that KRAS_B_WT is conserved in 16 species. (B) Luciferase reporter assay. Each of the 4 plasmids (150 ng) and a <i>Renilla</i> luciferase reporter (50 ng) were co-transfected into MIA PaCa-2 cells with precursor miR-126 (100 nM). Luciferase activity was assayed 48 hours after transfection. All experiments were independently repeated at least three times; the results are presented as mean±SD (**<i>P</i><0.01).