Since the expression of CSC-related markers has been shown to portend increased aggressiveness in some tumors such as pancreatic adenocarcinoma [21] and non small cell lung cancer [22] and since ALDH1 seems to be a reliable marker for CSCs, we evaluated whether ALDH1 expression could be associated with local pathologic tumor characteristics and clinical outcome in renal cell carcinoma. Here, ALDH1A1 is linked to hereditary clear cell renal cell carcinoma.