The method to generate the mouse model for mesenchymal chondrosarcoma is outlined in Figure 1A. The FLAG-tagged cDNA encoding a full coding region of human HEY1::NCOA2 was cloned into a pMYs-IRES-GFP retrovirus vector (Supplemental Figure 1A; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.160279DS1). Here, HEY1 is linked to chondrosarcoma.