S1PR2 and pulmonary arterial hypertension: In contrast, a quarter of samples in the SSc-PAH group displayed positivity for S1PR2-aAb (15/58, 25.9%), whereas a smaller percentage of SSc patients without PAH was positive for S1PR2-aAb (15/100, 15.0%), with the difference reaching statistical significance (P=0.0467) (Figure 4B).