Comparison of HERV-K gag mRNA expression in PBMC isolated from the blood of healthy controls (n = 135) and prostate cancer patients (n = 294) using previously published gag mRNA primer set. (a) HERV-K gag mRNA was significantly elevated in PBMC isolated from prostate cancer patients compared with the control population (Mann–Whitney test, P < 0.001). (b) HERV-K gag mRNA is significantly elevated in PBMC from African-American (AA) controls compared with European-American (EA) controls (Mann–Whitney test, P < 0.001), whereas there was no significant difference in the levels of HERV-K gag between African-American and European-American patients (Mann–Whitney test, P = 0.44). HERV-K gag was significantly elevated in patients compared with population controls in both African-Americans (Mann–Whitney test, P < 0.001) and European-Americans (Mann–Whitney test, P < 0.001).