In light of our results, we suggest the following guidelines for new studies of Tregs in a cancer context: (i) focus on the CD45RO+FOXP3high activated and CD45RO−FOXP3low resting subsets, and the CD25high fraction, (ii) determine the Treg/CD8 ratio, (iii) choose the study sample carefully (nest vs. stroma or intra- vs. peritumoral), (iv) annotate clinical data comprehensively. The gene discussed is CD8A; the disease is cancer.