- Patients must have metastatic cancer that overexpresses p53 as assessed by immunohistochemistry, as determined by positive staining of tumor sample. when compared to negative controls per procedure in Appendix 1. The immunohistochemical staining will be performed in the Pathology Laboratory Center for Cancer Research (CCR), National Cancer Institute (NCI) on fresh or archival tissue and will be supervised by Dr. Maria Merino. The criteria used to determine overexpression will be that used in the Laboratory of Dr. Curt Harris. Ten fields will be evaluated at 40 X magnification and if greater than 5% of cells stain positive, the tumor will be categorized as an overexpressor.