CXCR5 and pachyonychia congenita: Extensive studies have reported that the CXCL13/CXCR5 axis mediates PC cell migration, invasion, cell adhesion, and anti-apoptosis functions through regulating the intracellular signaling networks in an autocrine or paracrine fashion and forming an oncogenic microenvironment, which consists of multiple cell types, such as inflammatory cells and PC cells.