TGFBR3 gene expression levels are elevated in the mesenchymal stem-like (MSL) subtype of TNBC. A) Heat map representation of gene expression for 587 TNBC tumors for each TGF-β ligand and receptor. B) Quantification of average TGFBR3 gene expression across TNBC tumor subtypes, average based on individual TNBC tumor probe intensity values (**P = 0.004; ***P <0.0003 for a two-tailed Student’s t-test). C) Heat map of TGFBR3 mRNA expression in TNBC representative cell lines. D) Quantification of TGFBR3 gene expression across representative TNBC cell lines (**P = 0.004; for a two-tailed Student’s t-test, ns = not significant). E) qRT-PCR analysis of TGFBR3 average mRNA expression (2-ΔΔCt)  from representative TNBC cell lines; graph bars represent the mean of three replicates with SEM error bars. F) Immunoblot analysis of TβRIII protein expression in TNBC representative cell lines, results representative of two independent experiments. SEM, standard error of the mean; TNBC, triple negative breast cancer; TβRIII, type III transforming growth factor-beta receptor.