Furthermore, researchers in a recent study found that the levels of C-X-C motif chemokine ligand 4/platelet factor 4, which is platelet-specific, and antiangiogenic and profibrotic chemokines are increased in patients with SSc and correlate with the level of fibrosis as well as the occurrence and progression of pulmonary arterial hypertension [32]. This evidence concerns the gene PF4 and systemic sclerosis.