PDGFB and neoplasm: Because MCF-7, MDA-MB-231 and MIA-PaCa-2 cells highly expressed PDGF-B but the CM of later two tumor cell lines were unable to facilitate pericytes to attach more abundantly to the capillary-like structures as compared to MCF-7-CM, these studies indicate that some additional factor(s) is essential for proper adhesion of pericytes to the vessels, which is either missing or inhibited by aggressive cancer cells for metastatic spread.