Since osteoblasts are generally considered as one type of fibroblasts (40) and the conversion of fibroblasts to osteoblasts has been examined in multiple studies (41, 42), enrichment of EMP1+/COL3A1+ osteoblasts in BoM samples of prostate cancer also demonstrates the importance of fibroblasts during the BoM process. This evidence concerns the gene COL3A1 and prostate cancer.