However, in a panel of resistant GCTs that did either not respond to cisplatin-based chemotherapy or subsequently relapsed and resulted in the death of the patient, we have now identified a subset of tumors to contain TP53 mutations within exons 6-9. A cell line derived from one of these tumors (228A) displayed the same TP53 mutation as the tumor specimen, expressed only mutant TP53 mRNA, and exhibited a relative resistance to cisplatin in vitro in comparison to a cell line (218A) derived from a responsive tumor with wild-type TP53. The resistant cell line displayed a much reduced apoptotic cell death and did not exhibit an induction of transcription of the p53-responsive genes WAF1 and MDM2 following cisplatin treatment, compared to that observed in the sensitive cell line.