CXCL12 and gonorrhea: Xing et al. investigated the expression of CXCR4 and CXCL12 in 35 PAs (21 invasive and 14 non-invasive) patients who underwent surgical resection, and demonstrated that that there was a positive correlation between the level of CXCR4 and CXCL12 and the progression stage of PAs, suggesting that CXCR4 and CXCL12 played a role in the regulation of PAs invasiveness (45).