Figure 3.

Expression of MMP13 by BM-derived myofibroblasts. (A, B) MMP13 in situ hybridization demonstrated strong expression of MMP13 mRNA by stromal cells invading the tumor, whereas stromal cells bordering the tumor presented lower signal. (C, D) A combination of α-SMA immunostaining and MMP13 in situ hybridization revealed that MMP13 mRNA is expressed by myofibroblasts. (E, F) α-SMA-positive myofibroblasts bordering the tumor express only low amounts of MMP13 mRNA, whereas myofibroblasts within the tumor mass do express high amounts of MMP13 mRNA. (G, H) The expression of MMP13 by GFP⁺ BM-derived cells was illustrated by a combination of MMP13 in situ hybridization and GFP immunostaining. Representative images of in situ hybridization without and combined with immunoperoxidase stainings are presented in bright field (A, C, E, and G) and in dark field (B, D, F, and H); i, intratumoral; p, peritumoral. The graphs correspond to the density of MMP13 mRNA labeling as a function of the distance to brown staining of (I) α-SMA or (J) GFP. X₉₀ (percentile) means that 90% of values are below this distance.