PIWIL2 and neoplasm: It should be noted that little full length of Piwil2 proteins were detected in wt MEFs (Figure 5B) and human tumor cell lines (not shown) [1], this is consistent with our previous observations that full length PIWIL2 proteins were expressed in a lower level in normal somatic cells and tumor cell lines, while PL2L60 proteins were predominantly expressed in tumor cell lines [1, 13].