CXCR4 and pachyonychia congenita: Serum concentrations of both specific receptors for chemokines (CXCR4, p < 0.001 and CXCR2, p = 0.01) as well as the classical tumor marker (CEA, p < 0.001) and the marker of inflammation (CRP, p < 0.001) were statistically significantly higher in PC patients when compared to healthy volunteers (Table 2).