PDGF-BB is a cystine-linked homodimer PDGF family member with key roles in development, cell proliferation, cell survival, and angiogenesis (1,2). PDGF-BB is expressed by vascular endothelium, megakaryocytes and Leydig cells (2). PDGF-BB targets pericytes, fibroblasts, monocytes and other cell types (1-3). PDGF induces fibroblast growth and migration (3) and is a chemoattractant for monocytes and granulocytes. Precursor PDGF-BB is cleaved intracellularly to generate a form that contains a carboxy-terminal stretch that serves to retain PDGF-BB in the extracellular matrix. In a second cleavage event, the carboxy-terminal stretch is removed extracellularly to generate mature PDGF-BB (1,2). PDGF-BB binds to PDGFRbeta and induces receptor dimerization. Signaling is through the PI3K/Akt, JNK, and PLCgamma pathways (1, 2). PDGF-BB may have a role in some cancer types (2).