Slit3 promotes EC motility and migration. (A-B) Wound healing assay. The confluent EC monolayer was scratched to create a wounded gap (highlighted by the dashed lines) and then cultured with a supplement of BSA (1.3 nmol/L), recombinant Slit3 (0-0.80 nmol/L), or VEGF (1.5 nmol/L). After 24 hours, the gap width relative to the ones cultured with BSA was quantified. (C-D) Modified Boyden Chamber assay. BSA, Slit3, or VEGF was supplemented in the lower chamber, with HUVECs (C) or mouse lung ECs (D) loaded in the upper chamber. The data are presented as the -fold increase in number of cells migrated to the bottom side of the chamber relative to the BSA control. Data are summarized from at least 3 independent experiments in triplicate and presented as mean ± SD. Asterisk indicates statistical difference compared with the BSA treatment by Student t test (*P < .01; **P < .001).