Upregulating wild-type hMEPE/OF45 (but not mutant hMEPE/OF45) could stabilize CHK1 by reducing CHK1 interaction for its E3 ligases Cul1 or Cula4A; it increases the G2 checkpoint response and increases the resistance of tumour cells to IR or CPT treatment. Here, CUL1 is linked to neoplasm.