(A) 4T1 cells stably transfected with miR-98, anti-miR-98, or control GFP were seeded on tissue cultures plates containing 5% FBS for six 6 days for proliferation assays. *P < 0.05, **P< 0.01. Error bars, SEM (n=4). (B) The cells were seeded on tissue cultures plates (Upper) or Petri dishes (Lower) in serum-free conditions. Cell survival was monitored by counting the viable cells. **P< 0.01. Error bars indicate SEM (n=4). (C) The cells were mixed with Ypen cells and inoculated in Matrigel, followed by examination of tube formation. The Ypen cells formed larger complexes and longer tubes when mixed with the anti-miR-98-expressing cells compared with the GFP- and miR-98-transfected cells. (D) The cells, which had been labeled with green fluorescent dye DiO, were seeded on tissue culture plates. After overnight culture, endothelial Ypen cells, labeled with red fluorescent dye DiI, were inoculated on the top of the stably transfected cells. After 24 hours of co-culture, the Ypen cells cells were able to spread on the anti-miR-98 cells, but not on the GFP and miR-98 cells. (E) The cells were inoculated onto Matrigel in trans-well inserts. Three days after inoculation, the cells were stained with Coomassie Blue to examine cell invasion. The cells expressing anti-miR-98 exhibited stronger invasive activity than the others.