CXCR4 and pachyonychia congenita: Consistent with our findings, Singh et al. reported the association of gemcitabine with a dose and time-dependent increase in CXCR4 expression levels in PC cells and also demonstrated the role of the Chemokine Ligand-2 (CXCL2)/CXCR4 signaling axis in driving resistance to gemcitabine-induced apoptosis41.