IGFBP4 and GAS6, which code for proteins that inhibit IGF1R signaling, showed the highest significant downregulation (log fold changes <−4) in a four-way analysis, in which osteosarcoma pretreatment biopsies or cell lines were compared with osteoblastic cultures (n=3) or MSCs (n=12). Here, GAS6 is linked to osteosarcoma.