PINX1 and neoplasm: This discrepancy to previous studies [22,24] may be interpreted by the followings: 1) endogenous PinX1 level is already very low in tumor cells, therefore further downregulation has little effect on telomerase activity; 2) silencing PinX1 by transfection of PinX1-FAM-siRNA may be not long enough to observe substantial biological alterations of tumor cells.