CXCL1 and osteosarcoma: Integration of previous studies and our findings shows that dysregulation of CXCL1/CXCR2 and their downstream PI3K/Akt pathways is implicated in the metastasis progresses of osteosarcoma (invasion, migration, etc.)including several pathological progresses (tumorigenesis, proliferation, angiogenesis, and chemoresistance).