PF4 and vascular disorder: Of note, the various CXC chemokines, such as CXCL4 (ELR-) [47], CXCL5 (ELR+) [26], CXCL6 (ELR+) [27], CXCL12 (ELR−) [48], CXCL13 (ELR−) [24], and CXCL14 (ELR−) [49], are thought to be associated with the development of SSc vasculopathy.