Cancer-associated fibroblasts (CAFs) are an additional cell population contributing to the OB-BMST as indicated by: a) the association with a previously retrieved myofibroblasts/fibroblasts gene signature [12], b) the enrichment of CAF markers (i.e., Pdgfrb and Sparc) and recruiting factors (Tgfβ1, Tgfβ3, Fgf2 and Pdgfbb) [35], c) the pivotal position of CAF-derived ECM proteins (Fn1 and collagens) [36] in the protein network and d) the expression of ASPN and POSTN by myofibroblasts in primary and bone metastatic PCa. The gene discussed is FN1; the disease is cancer.