SPP1 and neoplasm: Developing tumors themselves modified the microenvironments by producing higher concentrations of osteopontin, SDF-1 (4T1), TGF-β (4T1 and E0771), CCL2, VEGF, FGF23 (E0771), and IL-6 (67NR), which influences the response to vitamin D3 supplementation/deficiency and calcitriol administration and leads to enhanced/decreased activation of lung fibroblasts and modulation of tumor tissue blood flow.