PDGFB and cancer: There was a significant reduction in PDGF-B expression in the tumor stroma in vivo as well as in BMPCs in vitro; however, our co-culture assay of BMPCs with KP-1N did not demonstrate upregulation of PDGF-B mRNA, suggesting that cancer-derived Hh ligand is unlikely to play a major role in the induction of PDGF-B.