Human adipose tissue-derived mesenchymal stem cells (hAMSCs) and primary human breast epithelial cells (PHBECs) in co-culture restrain their spreading and their proliferation reciprocally. (A) Bar graph showing the area of the mesh covered by monocultures of fluorescent protein-tagged hAMSCs or PHBECs, and of hAMSC/PHBEC co-cultures. Results represent means ± SD from three independent experiments; *P <0.01, **P <0.001. (B) Fluorescent images of Ki67 immunostained ex vivo cultures (red): 4',6-diamidino-2-phenylindole (DAPI) (blue) shows nuclei. Bar graph shows percent of Ki67-positive cells detected in each culture condition. Cells without fluorescent protein tags were stained. Scale bars 100 μm. hAMSC versus co-culture (CC), P = 7.39E-05; PHBEC versus CC, P = 0.01312; hAMSC versus PHBEC, P = 0.00018. (C) Representative flow cytometry dot plot showing separated red fluorescent protein (DsRed2)-expressing mesenchymal cells and enhanced green fluorescent protein (EGFP)-expressing epithelial cells from ex vivo co-culture prior to RNA extraction and transcription profiling. (D) Gene set enrichment analysis (GSEA) with PHBEC-specific genes and KEGG signatures comprising cell cycle genes (MSigDB), GSEA scores: mono/CC enrichment score (ES) = 0.58 normalized enrichment score (NES) = 2.38, CC/Mono ES = −0.58 NES = −2.38, false discovery rate (FDR) <0.0001, P <0.0001. (E) GSEA with hAMSC-specific genes and KEGG signatures comprising cell cycle genes (MSigDB), GSEA scores: mono/CC ES = 0.41, NES = 1.6, CC/Mono ES = −0.41, NES = −1.6, FDR = 0.0082, P = 0.005. (F) GSEA with PHBEC-specific genes and KEGG signatures comprising apoptosis genes (MSigDB), GSEA scores: mono/CC ES = 0.25, NES = 0.98, CC/Mono ES = −0.25, NES = −0.98, FDR = 0.866, P = 0.476. (G) GSEA with hAMSC-specific genes and KEGG signatures comprising apoptosis genes (MSigDB). GSEA scores: mono/CC ES = 0.31 NES = 1.17, CC/Mono ES = −0.31, NES = −1.17, FDR = 0.487, P = 0.207.