(C) A complete absence of p53 increases the accumulation of SOD1G85R mutant proteins in p53-/- HCT116 cells when compared with controls. Representative western blots (left panels) and quantification of SOD1G85R levels in the supernatant lysates are shown. The middle graph indicates the ratio of G85R to WT SOD1 proteins in the presence or absence of p53 with varying amounts of transfected mutant SOD1. The right graph panel shows the same data as shown in the middle panel, but normalized to the average SOD1G85R level for each amount of the transfected plasmid. Data represent means ± SEM. The numerical data used to make this figure can be found in S1 Data. 