CD28 and cancer: We found that ABCG2 expression shows a close link with T lymphocyte-related immune genes (CD28), T follicular helper cell associated immune genes (CD200 and CD200R1), and cancer-related genes, such as neuropilin-1 (NRP1), tumor necrosis factor receptor superfamily member 25 (TNFRSF25), and galectin-9 (LGALS9), in several different cancer types.