We cultured CAFs derived from TNBC xenograft tumors (HCI-001), and 3D co-culture assayed the CAFs and aggregated 4T1 cells (tumor cluster) in Matrigel. A. We examined the effects of PFD (triplicate). CAFs increased the tumor cluster size and PFD inhibited the size increased by CAFs (left panel). Also, CAFs increased the number of tumor clusters and PFD decreased the tumor cluster number increased by CAFs (right panel). *p<0.05 compared to tumor (0 μM). **p<0.05 or ***p<0.02 compared to 0 μM (Tumor + CAFs). B. We conducted immunofluorescence of the 3D Matrigel cultures by using anti-pan-cytokeratin (pCK, green, left panel), anti-vimentin (Vim, red, middle panel) and cleaved caspase-3 (cCSP3, red, left and green, middle panels, respectively) antibodies. DAPI (blue) stained nuclei. 4T1 tumor cells expressed both pan-cytokeratin and vimentin, and CAFs expressed vimentin. Therefore, pan-cytokeratin+ cells were 4T1 cells, and vimentin+ cells were either 4T1 cells or CAFs. Double-negative cells were regarded as other cell type. We counted the numbers of those cells (except 4T1 tumor clusters) with cleaved caspase-3 (representative photographs in left and middle panels) and quantified each apoptotic cells (right panel). We found that PFD induced apoptosis of 4T1 tumor cells and CAFs. C. We examined the effects of a TGF-β inhibitor (SB431542) in the 3D co-culture assay (triplicate). PFD decreased the tumor cluster size (left panel) and the tumor cluster number (right panel). *p<0.05 compared to tumor (0 μM). **p<0.01 compared to 0 μM (Tumor + CAFs).