On the other hand, it releases the intrinsic growth/osteogenic factors in bone matrix, including abundant quantities of insulin-like growth factor (IGF) and transforming growth factor β2 (TGFβ2), and relatively lower levels of bone morphogenetic protein (BMP), platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF), to stimulate the proliferation of metastatic cancer cells and activate osteoblasts (OB), hence accelerating osseous metastasis and inducing pathological nascent bone formation (3, 7). This evidence concerns the gene IGF1 and cancer.