PROM1 and systemic sclerosis: Consistent with previous reports [9, 10], the percentage of circulating CD34+CD133+VEGFR-2+ EPC in total CD34+ cells was significantly decreased in SSc patients (median 0.39, IQR 0.05−0.80) respect to HC (median 1.60, IQR 0.55−2.80) (p = 0.001).