STAT3 and gastric adenoma: In order to further investigate the extent to which miR-21 contributed to Stat3-dependent gastric adenoma development, we first asked whether the treatment of adenoma-free Gp130F/F mice with a chemically-modified generation 2.5 miR-21 antisense oligonucleotide (“antagomir”) [57] could suppress de novo tumor formation (Figure 4A).