4. Patients must have tumors over expressing p53 protein as assessed by immunohistochemistry, as determined by positive staining of tumor sample when compared to negative controls. The immunohistochemical staining will be performed in the Pathology Laboratory, CCR, NCI on fresh or archival tissue and will be supervised by Dr. Merino. The criteria used to determine overexpression will be that used in the Pathology Laboratory: Ten fields will be evaluated at 40 times magnification and if > 25% of cells stain positive, the tumor will be categorized as an overexpressor. Fresh tissue from a new biopsy will only be collected for IHC staining if the tumor is easily accessible and does not pose greater than minimal risk. A separate procedure consent will be required for all biopsy procedures.