For example, IGF is included in Garzón-Alvarado (2012) to simulate osteosclerosis because tumors are known to increase IGF levels and thus increase osteoblast activity. However, this work does not directly analyze the effect of IGF on bone cell dynamics. Although the modeling and analysis of IL-6 and MCSF is limited, some studies analyze their role in remodeling using perturbation or sensitivity analysis.