IDH2 and osteosarcoma: As presented in Figure 1B, all three cases included the IDH2-R172S mutant sequence (OS10, 14/16 (87.5%); OS11, 2/17 (11.8%); and OS12, 6/17 (35.3%)), demonstrating that all three osteosarcoma samples include IDH2-R172S mutations.