To test whether the loss of the tumor suppressors Ink4a and Arf would enable tumor formation or whether EWS-FLI1 was able to alter the tumors formed with Ink4a/Arf loss, cohorts of mice were generated such that Cre expression would delete the Ink4a/Arf locus as well as induce Ews-Fli1 translocation. The gene discussed is EWSR1; the disease is neoplasm.