In most Ewing sarcoma cell lines, DNA methyltransferase inhibition did not prompt a shift between isoforms, but an increase in both sfRON and flRON. In principle, this up-regulation of RON species as therapeutic targets may sensitize sarcoma cells to tyrosine kinase inhibitors that silence both MSP-mediated and MSP-independent tyrosine kinase activities (in contrast to the IMC-RON8 antibody). The gene discussed is MST1; the disease is Ewing sarcoma.