PINX1 and neoplasm: PinX1 knockout in mice can result in embryonic lethality in the PinX1 null mice (PinX1−/−) and the spontaneous development of a variety of malignant tumors in the PinX1 knockout heterozygous mice (PinX1+/−) [3], indicating that PinX1 is a potent telomerase inhibitor and a putative tumor suppressor [1, 4].