L-selectin plays a pivotal role in integrin-dependent neutrophil migration. (A-G) Chemotaxis of WT, Sell^−/−, and CD18^−/− neutrophils on fibronectin in response to a soluble CXCL1 gradient in vitro. Representative trajectory plots of WT (A), Sell^−/− (B), and CD18^−/− (C) neutrophils. Forward migration index (D), accumulated (E) and Euclidian (F) distance, and migration velocity (G) of chemotaxing neutrophils that were left untreated or were pretreated with LFA-1– or Mac-1–blocking antibody. A total of 40 cells was analyzed per experiment. n = 4. Data are mean ± standard error of the mean. *P = .05,**P = .01, ***P = .001, 1-way analysis of variance (ANOVA).