There was no significant detection of surface CTLA4 on monocytes by flow cytometry (0.10±0.02%, 13 replicates, n = 8 subjects) but we could readily detect intracellular CTLA4 in monocytes (89.93±1.40%, 30 replicates, n = 8 subjects), with no difference in either staining between a healthy subject and patients with melanoma (a representative example of surface and intracellular staining for CTLA4 in monocytes is included in Figure S5a). This evidence concerns the gene CTLA4 and melanoma.