CD28 and cancer: In contrast, the expression of genes regulating immune cell trafficking (e.g., CXCL13, CXCL9, XCL2, CCL5), T-cell activation and clonal expansion (e.g., CD27, CD28, ICOS, IL21, IL2) were massively decreased in 9p21-loss tumors across multiple cancer types/subtypes (Fig. 2f).