Importantly, expression in CAFs represents upregulated levels of Endo180 in the tumour stroma as illustrated by significantly higher MRC2 expression, alongside increased expression of two other fibroblast activation markers, α-smooth muscle actin (αSMA; ACTA2) and fibroblast activation protein (FAP), in a gene expression dataset of microdissected breast cancer stroma compared to adjacent normal tissue stroma34 (Fig. 1c). Here, MRC2 is linked to breast cancer.