To examine the relationship between miR-125a-5p and HDAC4 in patients, in situ hybridization analysis was performed with 5′-digoxygenin–labeled locked nucleic acid (LNA) probes of miR-125a-5p on Grade I (lymph node–negative and tumor size = 6 mm), Grade II (lymph node–negative and tumor size = 18 mm), and Grade III (lymph node–positive and tumor size = 24 mm) breast cancer tissues, followed by immunohistochemistry with an anti-digoxygenin antibody. The gene discussed is HDAC4; the disease is breast cancer.