Fig 1: Novel signaling circuit involved in recruitment of MSCs to the vicinity of GemOE tumors, in vitro and in vivo(A) The levels of geminin and SDF1/CXCL12 expressed in naïve HME, iGem9, iG197, iG240 or iG257 cells. (B) The levels of SDF1/CXCL12 secreted from naïve HME, iGem9, iG197, iG240 or iG257 cells grown under normoxic (N) or hypoxic (H) conditions as detected using specific ELISA assay. Experiments were done in triplicates 3 different times, ***represents p < 0.0001. (C) Schematic representation showing the experimental strategy used in (D and E). (D) Representative images showing the recruitment of GFP-MSC to the lower side of Boyden chambers inserts when naïve HME, iG240 or iG257 cells were layered on the lower wells and cells were grown in the presence of vehicle (1, 5 and 9, respectively), 10 µM imatinib (2, 6 and 10, respectively), 200 µM Glycyrrhizin (3, 7 and 11, respectively) or 10 µM AMD3100 (4, 8 and 12, respectively). (E) Quantitative analysis of the data represented in (D). Experiments were done in triplicates 3 different times, **represents p < 0.001 and ***represents p < 0.0001. (F) Schematic representation of the in vivo strategy used in the experiments used in G-P. (G) Representative images of cell lines generated from subcutaneously generated MDA-MB-231 tumors in Nu/Nu mice that were intracardiac injected with red-labeled MSCs and treated with vehicle, imatinib, glycyrrhizin or AMD3100 for 4 days (day -1, 0, 1 and 2 with regards to MSCs injection) collected 24 h after the last drugs administration (i.e. day 3 after MSCs injection). (H) Quantitative analysis of the data represented in (F). (I–P) Fluorescence immunohistochemical staining using anti-human CD105 (human MSC marker, green) and counterstained with DAPI (blue) of sections from the MDA-MB-231 tumors described in F. Except the in vivo part, all parts are of experiments that were done 2–3 separate times.