Quantifying PMS2 Expression by Western Blot

SDS‐PAGE and western blots were performed as described previously (D'Arcy et al., 2019 (link)). Antibodies used for the western blots include: PMS2 mouse monoclonal antibody (1:1000; Santa Cruz Biotechnology, Cat # sc‐25,315) and MLH1 mouse monoclonal antibody (1:1000; Santa Cruz Biotechnology, Cat # sc‐133,228 X). For the loading control, PCNA, a (D3H8P) XP rabbit monoclonal antibody (1:1000; Cell Signaling, Cat #13110S) was used. An ECL anti‐mouse IgG secondary antibody conjugated to horseradish peroxidase (HRP) (1:10,000, GE Healthcare NA931VS, from sheep) or anti‐rabbit IgG secondary antibody conjugated to HRP (1:10,000, GE Healthcare NA934V, from donkey) and Advansta Inc Westernbright Sirius—femtogram substrate were used to visualize antibody binding using a Bio‐Rad ChemiDoc imager. As performed previously, relative PMS2 expression was quantified and normalized to PCNA using ImageLab 5.2.1 software (Bio‐Rad). The mean ± SEM was derived from the cumulative data generated from three separate experiments. Statistical analysis was performed in GraphPad Prism 7 using an unpaired t‐test with Welch's correction where equal standard deviations are not assumed.