Mutations in TP53 (encoding the p53 protein) occur with a frequency of 5%–20% in Ewing's sarcoma, amplifications of MDM2 occur in 0%–10% of cases, and deletions of the CDKN2A locus (encoding overlapping p16INK4A and p14ARF transcripts) occur in about 15% of cases [30, 32, 34, 35]. Here, CDKN2A is linked to Ewing sarcoma.