CXCL1 and osteosarcoma: CXCL1 has higher expression in the tumor tissues compared to normal tissues, and the levels of CXCL1 expression may increase with the tumor progression, many factors were found to relate to this phenomenon, including the extracellular vesicles secreted by osteosarcoma cells, pH levels, and other cytokines released by tumor-relating cells (90, 91).