ICOS and breast cancer: In addition, the expression levels of CD80 and CD86 (the B7 co-stimulatory molecules) and ICOS-L, which is the ligand for the T-cell-specific cell surface receptor ICOS and acts as a costimulatory signal for T-cell proliferation and cytokine secretion, were not changed (p>0.05) on HLA-A2+ breast cancer, colon cancer and pancreatic cancer cell lines after lenalidomide treatment (Figure 3B).