CCL2 and pachyonychia congenita: In addition, Li et al. discovered that HIF-1α, combining with chemotactic factor 2 (CCL2), recruits macrophages to activate pancreatic stellate cells, promoting the secretion of extracellular matrix (ECM) in PC, aggravating hypoxia of the pancreatic microenvironment, and promoting the progression of PC (Li et al., 2016).