As illustrated in Fig 7, more detailed immunohistochemical analysis of serial/semi- serial sections prepared from fixed co-culture spheroids using epithelial and fibroblast-specific markers, showed that fibroblasts seemed to be surrounded by epithelial cells, a phenotype not dissimilar to the relationship of stromal fibroblasts within breast tumours, illustrated by the breast cancer TMA core, shown as an insert to Fig 7D, where stromal fibroblasts were identified by α-SMA staining. This evidence concerns the gene ACTA1 and breast cancer.