NKG2D deficiency was identified in human breast cancer tissues, and MCT4 expression was detected after 7acc1 (a MCT4 inhibitor) treatment and ShMCT4. A, Representative images of CD56 and NKG2D expression detected by immunohistochemistry in four randomly selected breast cancer patients’ tissues. B, Statistical analyses of the CD56+ and NKG2D+ cell densities in the breast cancer tissues and the nonmalignant hyperplasia tissues from the patients. C, NKG2D mRNA levels in 1106 samples from breast cancer and normal breast tissues were analyzed using the starBase Pan‐Cancer Analysis Platform. D, The protein expression of MCT4 in the murine breast cancer cell line 4T1 treated with 7acc1 (0.1 mmol/L) or transfected with different ShMCT4 vectors (weak “1,” medium “2,” and strong “3”). *P < 0.05