CCL1 (I-309) and vCCL1 (vMIP-1) induce chemotaxis of human vascular smooth muscle cells (VSMCs). Varying concentrations of either CCL1 or vCCL1 were placed in the lower wells, and cultured VSMCs were added to the upper wells of the Neuroprobe chemotaxis chambers. The Neuroprobe membrane (5-μm pores) was coated with fibronectin. Incubation, staining, and counting of the cells was performed as described in “Materials and methods.” Both CCL1 and vCCL1 induced chemotaxis of VSMCs in a bell-shaped distribution, characteristic of a chemotactic response. *P < .001 comparing VSMCs stimulated with either CCL1 or vCCL1 against cells stimulated with buffer. (hpf indicates high-power field.) Error bars represent SD.