Runx2 knockdown inhibits MM progression in vivo. (A) Expression of Runx2 in 2 Runx2 k/d 5TGM1 cell lines (Runx2 shRNA #90– and Runx2 shRNA #91–transfected 5TGM1 cells) was probed by western blot. Both Runx2 shRNA #90 and #91 decreased the expression of Runx2 compared with NT control. (B) Serum IgG2bκ was measured by ELISA 6 weeks after IV injection of NT control or Runx2 k/d 5TGM1 cells. Error bars represent mean ± SEM (n = 10 animals per group). Significant differences between groups are indicated by P value. (C) H&E-stained bone sections from mice injected IV with either NT control or Runx2 k/d 5TGM1 cells. Tumors were present in mice injected with NT cells, but not in the mice injected with Runx2 k/d cells (original magnification, ×100). Inset, Abundant myeloma cells in NT-bearing mice compared with Runx2 k/d 5TGM1 cell-injected mice. (D) Survival was significantly increased in mice injected IV with 5TGM1 Runx2 k/d cells (clone #90 and #91) compared with those injected with NT 5TGM1 cells. (E) Six weeks after intratibial injection of Runx2 k/d or NT 5TGM1 cells, levels of serum IgG2bκ were measured by ELISA. Error bars represent mean ± SEM (n = 10 animals per group). Significant differences between groups are indicated by P value. (F) Western blot shows reduction of Runx2 expression in MM.1R cells transduced with Runx2 shRNA compared with wild-type (WT) or NT control cells. (G) Six weeks after s.c. injection of NT or Runx2 k/d human MM.1R cells, serum human Ig λ light chain was measured by ELISA. Error bars represent mean ± SEM (n = 10 animals per group). Significant differences between groups are indicated by P value.