POSTN and neoplasm: Taken together, these findings suggest that the enrichment in proliferation signatures in bulk samples (i.e. pooling together stromal and tumor epithelial signatures, in the Beaujon or ICGC data set) from tumors rich in POSTN‐positive CAFs is attributable to high cellular proliferation rate in the stromal (i.e. CAF or immune cells) (Figure 2A) rather than the tumor epithelial compartment.