where p is the probability that the protein was hit for at least k HIV/KS patients, n is the total number of HIV/KS patients, and f 1 is the frequency of the protein in the comparison group (either lymphoma or healthy normals). Proteins were selected as a significant biomarker for HIV 1 /KS patients only if they had at least 50% frequency in HIV 1 /KS patients, the enrichment score ES was larger than 1.6, and the P value was less than .005.