VHL and nonpapillary renal cell carcinoma: Despite that the VHL gene mutation is considered to be an early oncogenic event in ccRCC, our recent work shows that the expression of pVHL in human ccRCC is heterogeneous, whereby population with the presence (VHL(+) cells) and the absence of wildtype pVHL (VHL(−) cells) are observed to coexist side by side in the same tumor [15].