POU5F1 and renal cell carcinoma: According to Moreira's [34] report, in lung cancers, stem cell markers are expressed with different patterns seen for different histological types and degrees of differentiation, considering that our RCC specimens were restricted to clear cell RCC (28 in 30), we still cannot eliminate OCT4 and NANOG as non-potential biomarkers for RCC and more comprehensive studies are needed to elucidate their importance.