Clustering of protein expression profiles. Clustering analysis divides normalized protein expression patterns into 7 distinct clusters. Three clusters have high expression in 1 subset compared with the others (clusters 1, 3, and 5 for CD62L^dim, banded, and segmented neutrophils, respectively), 2 clusters have decreased expression in 1 subset (clusters 2 and 7 for CD62L^dim and banded neutrophils, respectively), and 2 clusters have gradually increasing (cluster 6) or decreasing (cluster 4) protein expression levels from banded to segmented and CD62L_dim. Each line represents the expression pattern of 1 protein. Line colors indicate the cluster membership value (ie, the higher the membership value, the more similar to the cluster average). A minimum cluster membership value of 0.33 was used for further analysis. Numbers between brackets indicate the number of proteins in each cluster with cluster membership values above 0.33.