In contrast, only two non-biomechanical spatiotemporal models of bone remodeling explicitly model RANK-RANKL-OPG and TGF-β (Table ). These models, and , are 1D spatial extensions of the same temporal model. evaluates whether the biological pathways in are necessary and sufficient to capture the expected arrangement of cells in cortical bone and concludes that the model requires an additional differentiation stage for osteoclasts. Although this model includes more explicit parameters than other biochemical models, the values are not quantitatively compared to data. The model relies on theoretical simulation results and temporal study parameters and only estimates new parameters as needed. This is a common approach in spatiotemporal models, including those by and . notes that there is no parameter fitting in their study and acknowledges that experimental data are necessary to quantify and validate the model. Yet, even though calibrates a model with multiple datasets, the model is limited to fewer parameters and fewer explicit biological interactions. The authors of offer the perspective that more parameters "compromise the balance between reliability and realism" by increasing the uncertainty of the model .