CXCL12 and infection: BMDC migration was next examined in vitro using transwell chambers and the chemoattractant fMIFL to mimic microbial peptides found at the site of infection, SDF-1 (also known as CXCL12), a chemokine expressed by lymphatic vessels19, or CCL21 (also known as Exodus-2 or SLC), the major chemokine eliciting DC homing to lymph nodes (Fig. 2b, Supplementary Fig. 2b).