PIK3R2 and renal cell carcinoma associated with Xp11.2 translocations/TFE3 gene fusions: The S-TFE cell line had the ASPL-TFE3 gene fusion, while the UOK120 and UOK146 cell lines had the PRCC-TFE3 gene fusion and showed PIK3R2 overexpression, which was associated with the aggressiveness of Xp11.2 tRCC.