Fig. 1.

Human epidermal growth factor receptor 2 (Her2)-positive (Her2+) breast cancer brain metastasis (BBM) cells express high levels of phosphorylated neurotrophin receptor tropomyosin-related kinase B (p-TrkB). a Quantification of Her2 and TrkB in resected Her2+ (n = 8) and triple negative (TN) (n = 4) primary breast cancer tissue (left) and Her2+ (n = 3) and TN (n = 3) breast-to-brain metastases (*p < 0.05, **p < 0.01, ***p < 0.001; bars indicate SEM). b Representative immunofluorescence staining of primary breast cancer (left, n = 4) and breast-to-brain metastasis tissue (right, n = 4) from four patients (Pt). Tissue was stained for Her2 (green) and p-TrkB (red). Nuclear counter staining was done with 4',6-diamidino-2-phenylindole (DAPI, blue). c Immunofluorescence staining of p-TrkB in BBM1 and 231Br brain metastasis breast cancer cell lines. d Western blot analysis of p-TrkB and total TrkB in BBM1, BBM2, 361, and SkBr3 cells