Transfection of miR-199a-5p mimics boosted the fraction of cells in G0 phase, from 68% to 93%, and reduced G2/M and S phase cell fraction from 22.9% to 3.7% and 9% to 3.3%, respectively. Transfection of CTGF siRNA also exhibited similar effect on malignant thyroid cells. In contrast, transfection of miR-199a-5p inhibitors suppressed the fraction of cells in G0 phase from 68% to 60.9%, and increased fraction of cells in G2/M phase from 22.9% to 25.7%, and in S phase from 9.1% to 13.4%.