CHEK1 and neoplasm: In this study, on the basis of our previous report about the new role of rMEPE/OF45 in protecting cells from DNA damage-induced killing (Liu et al, 2009), we investigate whether hMEPE/OF45 is generally expressed in different types of tumour cells, whether the expression levels were relevant to the resistance of tumour cells to DNA damage inducers and whether, similar to rMEPE/OF45, hMEPE/OF45 (as a cofactor of CHK1) could be a new target for sensitizing human tumour cells to DNA damage inducers.