We performed immunohistochemistry for cathepsin K on 14 genetically confirmed t(X;1)(p11;q21) carcinomas, harboring the PRCC-TFE3 gene fusion.     ///    "However, 12 of 14 PRCC-TFE3 carcinomas expressed cathepsin K."    ///    "However, 12 of 14 PRCC-TFE3 carcinomas expressed cathepsin K. "    ///    "The difference in expression of cathepsin K between the PRCC-TFE3 and ASPSCR1-TFE3 carcinomas, together with the observed clinical differences between these subtypes of Xp11 translocation carcinomas, suggests the possibility of functional differences between these two related fusion proteins.. "