JAK2 and breast carcinoma: These findings highlight a novel molecular mechanism indirectly regulating PD‐L1 through the STAT4‐related pathway: IL‐12R/JAK2–STAT3–STAT4/PD‐L1, and it has potential application in predicting anti‐PD‐1 immunotherapy response, which may pave the way for stratified immunotherapy in breast cancer.