Physiologically, the appearance of CD70 is largely restricted to transient expression on antigen-activated T and B cells, natural killer cells and mature dendritic cells (23), but aberrant CD70 expression has been reported in many hematological cancers and several solid tumors (22, 26), including RCC where it is associated with metastasis and poor survival (23). This evidence concerns the gene CD70 and hematopoietic and lymphoid cell neoplasm.