TFE3 and renal cell carcinoma: To investigate this hypothesis, activation of the two signaling pathways and downstream factors, including phosphorylated mTOR (p-mTOR), phosphorylated MAPK (p-MAPK), 4EBP1, p-4EBP1 and phosphorylated ribosomal protein S6 kinase (p-S6K), were detected using immunohistochemistry in 36 adult Xp11.2 RCC patients who were confirmed by the TFE3 break-apart fluorescence in situ hybridization (FISH) assay.