Over-expression of miR-145 in colon cancer HCT-116 cells by stably transfected pCMV/miR-145 downregulates miR-21 and induces differentiation, inhibits stemness and produces no visible tumors in SCID mice. (A) qRT-PCR showing up-regulation of mature miR-145 and down regulation of miR-21 in HCT-116 cells that were stably transfected with pCMV/miR-145 plasmid or the corresponding vector, *P < 0.001. (B) Western-blot showing decreased expression of Sox2 and increased expression of CK-20 in miR-145 over-expressing HCT-116 cells, compared to the corresponding vector-transfected control cells. β-actin was used as a loading control, (C) Representative photographs showing colonospheres formed by the cells from miR-145 expressing clones, derived from HCT-116 cells, stably transfected with pCMV-miR-145 plasmid or the corresponding vector (top panel), histogram showing the number of colonspheres formed by miR-145 over-expressing HCT-116 cells, compared to the corresponding vector-transfected control cells (bottom panel, *P < 0.001), (D) while administration of miR-145 over-expressing HCT-116 cells produces no visible tumors in SCID mice, the vector-transfected HCT-116 cells (control) induces large tumors in SCID mice. The data represent means of three independent experiments.