To date, several resolvases have been observed to catalyze the resolution of G4 DNA structures back to the single-stranded DNA, such as viral SV40 large T-antigen helicase,16 human Werner's syndrome (WRN), and Bloom's syndrome (BLM) helicase,17DHX36,18, 19DHX9,20DDX11,21RTEL1,22 and PIF1.23 The deficiency of these resolvases often leads to embryonic lethality, genomic instability, unintegrated telomere, and senescence.24, 25, 26, 27, 28 Thus, the functional regulation G4 DNA resolvases appears to be indispensable in the normal development and physiological functions of various types of cells. This evidence concerns the gene PIF1 and Werner syndrome.