We found that the deletion of p53, specifically in Fgfr3+ cells with Trp53-floxed mice, drives Fgfr3+ ESCs to develop into osteosarcoma-like bone tumours, supporting that Fgfr3+ endosteal cells can be a cellular source of osteosarcoma (figure 3). Here, FGFR3 is linked to osteosarcoma.