PDGFRB and systemic sclerosis: In this context, it is reasonable to suggest that physiological aab against GPCRs9, such as functional aab targeting EDNRA15, and other functional aab, such as those targeting growth factor receptors including anti-PDGFR antibodies49 previously characterized in patients with SSc, could also regulate a myriad of biological mechanisms in synergism with endogenous ligands50,51.