BTNL9 and breast cancer: Because γδ T cells are involved in breast cancer (39, 40), we compared survival in high vs. low expression of BTN family in breast cancer and found low expressions of BTN1A1 (HR = 0.73, p = 1.3e-08), BTN2A1 (HR = 0.75, p = 3.7e-07), BTN2A2 (HR = 0.83, p = 0.00056), BTN2A3 (HR = 0.73, p = 2.2e-08), BTN3A1 (HR = 0.72, p = 2.3e-09), BTN3A2 (HR = 0.89, p = 0.042), BTN3A3 (HR = 0.86, p = 0.0064), BTNL2 (HR = 0.78, p = 8e-06), BTNL3 (HR = 0.71, p = 1.2e-09), and BTNL9 (HR = 0.62, p = 9.4e-10) were significantly correlated with worse OS of breast cancer (Figure 5C).