SP1 was a directly targeted gene of miR-149 in vitro. (A) Bioinformatics software assessed that SP1 mRNA contained a miR-149 seed match at position 3809–3815 of the SP1 3′-UTR. (B) miR-149 significantly inhibited the SP1 Wt but not the SP1 Mut luciferase activity in Tca8113 and CAL-27 cells. (C) Western blotting was performed to explore whether SP1 was downregulated at the protein level subsequent to transfection with miR-149 in tongue squamous cell carcinoma cells. The analysis revealed that SP1 was significantly downregulated in Tca8113 and CAL-27 cells subsequent to transfection with miR-149. SP1, specificity protein 1; miR, mircoRNA; Wt, wild-type; Mut, mutant; UTR, untranslated region; NC, microRNA mimics negative control.