Surface plasmon resonance assay of the binding of CX-01 to CXCL12α. (A) BIAcore sensorgrams for the binding of 100 nM CXCL12α after preincubation with different concentrations of CX-01 (0, 1, 5, 10, 50, 100, 1000, and 2000 nM). (B) Competition assay shows the CX-01 concentration (50% inhibitory concentration = 4.7 nM or 0.055 μg/mL) that inhibits 50% of the maximum CXCL12α attachment response to immobilized heparin.