Among the novel fusions, none of the NONO-TFE3 rearranged renal cell carcinomas have been shown to express cathepsin K, whereas RBM10-TFE3 rearranged renal cell carcinoma [33] and some MED15-TFE3 [34] rearranged renal cell carcinoma are reactive for this marker. This evidence concerns the gene CTSK and hereditary clear cell renal cell carcinoma.