PDGFRA and systemic sclerosis: To determine the effect of blocking PDGFR-α expression on fibroblast transdifferentiation to myofibroblasts in SSc, the same numbers of SSc fibroblasts were transfected for 48 hours with siRNA-I (siRNA1495), siRNA-II (siRNA2284), siRNA-III (siRNA3188), siRNA-NC (normal control), and normal control.