PRF1 and breast cancer: We found that SLAMF6 expression was highly correlated not only with the expression of T-cell markers (CD3E, CD8B, CD8A, and CD4) but also with upregulation of TCF7, PDCD1 encoding PD-1, GZMK, and effector-associated genes including IFNG and PRF1 in breast cancer (Fig. 2A).