CD28 and melanoma: Previously, in a clinical study of long term tumor specific T cell memory function in melanoma patients, we elucidated the multiparameter phenotype of tumor specific TCM (CCR7+CD45RA-CD57-CD27+CD28+), and a second potentially early TCM precursor which we referred to as TCMRA (CCR7+CD45RA+CD57-CD27+CD28+) [8].