MKI67 and nonpapillary renal cell carcinoma: The predominant network upregulated in VHLmut cultures compared to the matched primary tissues was proliferation, which is also not surprising given that the cultured cells are proliferating in response to culture conditions, whereas the proliferation index in ccRCC tumor tissues as defined by Ki67 staining is in general quite low (median 7.3 % in one study of 176 patients) [38].