Transcription Factor E3 (TFE3) is a transcription factor that binds to the MUE3-type E-box sequences involved in TGF-β signalling. Anti-TFE3 staining is the most sensitive and specific indicator of Xp11 translocation renal cell carcinomas. Since alveolar soft part sarcoma (ASPS) is characterized by a specific chromosomal rearrangement resulting in a chimeric transcription factor (ASPSCR1-TFE3), this TFE3 IVD antibody is also a useful diagnostic tool for recognizing ASPS.