To investigate if fusion protein MICA-G129R could enhance the cytotoxicity of NK cells on PRLR-positive breast cancer cells, the control and MICA-G129R conditioned media were added to the co-culture of NK-92 cells and T-47D cells at different effector/target ratios (5:1, 2:1, 1:1, and 1:2) for 24 hours and the cytotoxicity on T-47D cells was measured using a lactate dehydrogenase (LDH) cytotoxicity assay. This evidence concerns the gene MICA and breast cancer.