NANOG and neoplasm: The mRNA levels of all Piwi-like genes studied were positively correlated to tumor size (Piwi-like 2: rs = 0.21; p = 0.018; Piwi-like 3: rs = 0.20; p = 0.024; and Piwi-like 4: rs = 0.18; p = 0.041), Next, we investigated the correlation of Piwi-like 2–4 mRNAs with other stem cell-associated genes (Nanog, Oct3/4 and survivin).