The functional domain of the TFE3 gene fused with the promoter of other genes, housekeeping gene usually, resulting to the TFE3 protein is constitutively overexpressed in Xp11.2 tRCC which can be specifically identified by IHC (immunohistochemistry) [4, 5]. This evidence concerns the gene TFE3 and renal cell carcinoma associated with Xp11.2 translocations/TFE3 gene fusions.