Fig. 1: Organization of BCC in STEMs is determined by MSC-EC interactions.

a Brightfield and fluorescence microscopy images (MCF-7/BFP, EC/tdTomato, and MSC/GFP) of MCF STEMs, scale bar: 200 µm. b Brightfield and fluorescence microscopy images (MDA-231/BFP, EC/tdTomato, and MSC/GFP) of MDA STEMs, scale bar: 200 µm. c Pearson correlation coefficients (PCCs) of MDA/MSC, MSC/EC(MDA), MCF/MSC, MSC/EC(MCF) of STEMs after 10 days, n = 5. d Fluorescence images of cryosections of MDA and MCF STEMs on day 10 showing the distinct differences in the distribution of MSC and the organization of EC in the two systems. Note the close association between MSC and BC in MDA STEMs, which is lacking in the MCF STEMs, scale bar of the left image: 100 µm, scale bar of the right image: 200 µm. e PCCs of MDA/MSC, MSC/EC(MDA), MCF/MSC, MSC/EC(MCF) of cryosections after 10 days, n = 5.