Fig. 4

 H&E and immunohistochemistry (IHC) staining for neurokinin 1 receptor (NK1R) expression in breast cancer tissues and positive control. a). H&E staining of low NK1R expression in breast cancer tissue. b). H&E staining of high NK1R expression in breast cancer tissue. c-k). IHC staining of NK1R manifested mainly in nucleus and cytoplasm in: c). Positive control tissue (brain tissue). d). Luminal A breast cancer subtype (low expression level ≤ 1). e). Luminal A breast cancer subtype (high expression level > 1). f). HER2-enriched breast cancer subtype (low expression level ≤ 1). g). HER2-enriched breast cancer subtype (high expression level > 1). h). Triple positive breast cancer subtype (low expression level ≤ 1). i). Triple positive breast cancer subtype (high expression level > 1). j). Triple negative breast cancer subtype (low expression level ≤ 1). k). Triple negative breast cancer subtype (high expression level > 1). Arrows indicate the positively stained cells. Scale bar: 400 × (40X objective lens x 10X ocular lens = 20 μm)