FIG. 5.

hMLH1 is required for full induction of hPMS1 and hPMS2 in response to DNA damage. hMLH1-deficient HCT 116 cells were transfected with pCMV-SPORT6-hMLH1 or an empty vector by a double-electroporation protocol (see Materials and Methods) and treated with NCS (80 ng/ml) (upper panels) or MNU (2 mM) (lower panels) for the indicated periods of time. Cell lysates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the immunoblots were probed with antibodies specific to hMLH1, hPMS1, and hPMS2. PCNA immunoblotting was performed to ensure equal levels of protein loading. The intensity of hPMS signals was quantified by densitometry. The relative intensity compared to that of the 0-h sample is shown below each panel.