RUNX1T1 and osteosarcoma: As confirmed by Western blotting, VprBP is readily detectable in U2OS human osteosarcoma cells, and shows little changes in its levels following treatment with etoposide and doxorubicin which are topoisomerase II-targeted, DNA cleavage-inducing agents (Fig. 2A, Supplementary Fig. S2A, VprBP, Eto, and Dox).