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. This evidence concerns the gene CDKN2A and neoplasm.