Figure. Concentration-dependent activation of CXCR5 by CXCL13. Reporter cells were transfected with either the expression plasmid for C-X-C motif chemo­kine receptor 5 (CXCR5) or the mock plasmid and treated with various concentrations of C-X-C motif chemo­kine ligand 13 (CXCL13). Data points shown are the mean ± SEM of an experiment performed in triplicate, and the curve is a fit to Hill equation with an EC50 of 36 nM.