To investigate the effect of FGF2-SPIONs on the tumor stroma (CAFs)-induced effect on the tumor growth in a complex 3D microenvironment in vitro, we established a 3D heterospheroid tumor model by co-culturing PANC-1 pancreatic tumor cells and hPSCs, as illustrated in Figure 6A. Here, FGF2 is linked to neoplasm.