CXCR2 and pachyonychia congenita: A number of previous studies have investigated if C-X-C motif chemokine receptor (CXCR) 2 and C-X-C motif chemokine receptor (CXCR) 4 play an important role in tumor proliferation, invasion, angiogenesis, metastasis and migration in numerous types of malignancies, including pancreatic cancer (PC) [5,6,7,8,9,10,11,12,13].