Thrombospondin 4 (THBS4) is an extracellular glycoprotein known to have roles in cellular migration, adhesion and attachment, as well as proliferation. Data to support a role in cancer biology is steadily increasing, including for tumours of the gastrointestinal tract and prostate. We present a meta-analysis of breast cancer gene expression data investigating the differences between invasive ductal and invasive lobular carcinomas. Using this approach we identified THBS4 as a candidate biomarker of the invasive lobular breast cancer phenotype. The attempt to demonstrate this differential expression at the protein level with immunohistochemistry, however, demonstrated significant increases in expression in cancer associated stroma relative to neoplastic epithelium (P<0.0001), normal epithelium (P<0.0001) and normal stroma (P=0.0033) but no significant difference in expression of THBS4 between the ductal and lobular histological phenotypes. We discuss the impact of this data on the reliability of gene expression data interpretation without sufficient protein validation, especially with respect to clinical samples. This data also provides further support for the idea that the interplay between tumour cells and their microenvironment critically is important for the development and progression of malignancy.