PROM1 and systemic sclerosis: Total numbers of circulating eEPCs (CD133+/Flk-1+ cells) significantly differed between controls and SSc patients: Controls 14.6 ± 2.9 %; SSc all 0.4 ± 0.1 %; lSSc ±0.4 0.1 %; dSSc 0.5 ± 0.3 %; the respective p-values were: Controls vs. SSc all p < 0.0001; Controls vs. lSSc p < 0.0001; Controls vs. dSSc p = 0.04 (Fig. 1).