CD276 and breast cancer: B7-H3, which belongs to the B7 superfamily, is a type I transmembrane protein originally detected in immune cells, such as dendritic cells and specific T cell subsets [27, 28], as well as in a variety of human solid tumor cells, including melanoma [29], breast cancer [30], ovarian cancer [31], pancreatic cancer [32], and gliomas [33, 34].