PDGFRB and systemic sclerosis: Nevertheless, in the wake of subsequent studies reporting that these antibodies did not exert an agonistic activity and were not SSc-specific [100,101], the authors performed additional experiments and concluded that in the same SSc patient both agonistic and nonagonistic anti-PDGFR autoantibodies may coexist, and that stimulatory autoantibodies can be detected only in SSc but not in healthy individuals or patients with other connective tissue diseases [102,103].