Is PDGF really important? Testing the hypotheses.

Platelet-derived growth factor (PDGF) has been proposed to be one of the growth factors that drive proliferation during normal development and in various pathological conditions. Support for these hypotheses has been largely circumstantial. We discuss the pros and cons of the different experimental approaches that have been taken to test these hypotheses, and evaluate the information to be gained by characterizing the consequences of deletion of one of the PDGF receptor genes in the Patch mutant mouse.