CD28 and melanoma: By contrast, expression of CD27 and CD28 was highly variable in both day 14 γδT cells derived from melanoma patients (3–19 and 2–76%, respectively; n = 4) and healthy donors (2–19 and 15–86%, respectively; n = 5), reminiscent of effector memory (TEM) cells rather than terminally differentiated effector memory (TEMRA) cells.