Fig. 7

miR-19b-3p downregulates SMAD4 expression by directly targeting its 3′ UTR. a and b Endogenous candidate target genes expression were significantly upregulated in SW480 (a, qRT-PCR and b, western blotting) and RKO (a, qRT-PCR and b, western blotting) cells transfected with miR-19b-3p inhibitor compared with negative control ones. c The 3′ UTR of SMAD4 mRNA contains a complementary binding site for the seed region of miR-19b-3p. SMAD4 mut is a mutant with substitutions in the complementary region as a negative control. d The luciferase activity was detected after transfection of pmirGLO luciferase reporter vector (pmirGLO-Vector, pmirGLO-SMAD4 3’UTR-wt or pmirGLO-SMAD4 3’UTR-mut) into the miR-19b-3p mimics or miRNA mimics negative control transfected SW480 cells. **, P < 0.01. e Representative images from in situ hybridization and immunohistochemistry both in the same location of tissue microarray, showing that miR-19b-3p expression was significantly negatively correlated with SMAD4 expression. See also Additional file 3: Table S3