To examine the correlation of miR‐34 and NK1R in breast cancer, MDA‐MB‐231 and MCF‐7 cells, which express high level of NK1R‐Tr, were transfected with miR‐34a‐3p, miR‐34a‐5p, miR‐34b‐3p, miR‐34b‐5p, miR‐34c‐3p, miR‐34c‐5p mimics and inhibitors. Here, TACR1 is linked to breast cancer.