This observation is another strong implication that drug efficiency evaluation should be conducted using an adequate 3D model with incorporated biomechanical cues so as to avoid discrepancies between clinical and in vitro results.69 Likewise, another study confirmed that IGF1 production by Ewing sarcoma cells is shear stress dependent but a negligible effect of flow on IGF-1R secretion was observed.70 In that study, to imitate the heterogeneous tumor structure, polypropylene fumarate scaffolds were 3D printed with pore size gradients. Here, IGF1 is linked to Ewing sarcoma.