PDGF, a ligand of PDGFR, has 4 isofoms, A-, B-, C- and D-chains, and forms hetero and/or homo dimers, PDGF-AA, -AB, -BB, -CC, -DD. On the other hand, PDGFR has 2 isoforms, α- and β-chains and forms hetero and/or homo dimers, PDGFR-αα, -αβ and -ββ. PDGF-A and PDGF-C binds specifically to PDGFR-α, PDGF-B binds to PDGFR-α and PDGFR-β, and PDGF-D binds specifically to PDGFR-β. In other words, PDGF-AA and PDGF-CC can activate only PDGF-αα, while PDGF-AB can activate PDGFR-αα and PDGFR-αβ, and PDGF-BB can activate PDGFR-αα, -αβ and -ββ. While, PDGF-DD has been reported to be able to activate PDGFR-αβ as well as PDGFR -ββ. When the receptor is dimerized, tyrosine kinase activity in the intracellular region increases and auto-phosphorylation of the tyrosine residue takes place. For research use only, not for use in diagnostic procedures.