Figure 4. Principal component analysis of kidney tissue in female and male donors. (A) Unbiased principal component analysis (PCA) of all female donors showed the most variation of genes on the principal component (PC) axis 1 and some clustering of the two intervention groups is shown. (B) The PCA of the male donors was based on only three kidneys in the PCR group, and showed little variation on PC axis 2. Principal component (PC) 1 is depicted on the x-axis and PC2 is depicted on the y-axis, followed by the percentage of variance explained by each axis. Each symbol represents one sample of one donor. Samples of the same group are shown in the same color. PCR = protein and caloric dietary restriction.