CD28 and breast cancer: To identify factors that can induce CD177 expression on Treg cells, we purified human PB Treg cells or CD4 Tconv cells (Fig. 4f) from breast cancer patients, or splenic Treg cells or CD4 Tconv from MC38 tumor-bearing mice (Fig. 4g), either non-stimulated (ns) or treated with anti-CD3/CD28 and IL-2.