Erythroblastic island formation in the presence and absence of peptides blocking adhesion of ICAM-4 to αV integrins. Model of extracellular domain of ICAM-4 is shown revealing its solvent exposed surface in 3 orientations rotated 120° to each other. The region of ICAM-4 involved in adhesion to αV integrins is shown in yellow and green. Yellow designates area of FVW peptide sequence and green depicts location of ATSR peptide sequence (A). Histogram of percentage of islands formed in the presence of 0.5 to 1.0 mM FWV peptide (n = 11), 1.0 to 2.0 mM FWV peptide (n = 16), and 2.0 to 3.0 mM FWV peptide (n = 8) compared to islands formed in media alone. *P = .02, **P < .001, ***P < .001 when compared to islands formed in media alone (B). Histogram of percentage of islands formed in the presence of 0.5 to 1.0 mM ATSR peptide (n = 3), 1.0 to 2.0 mM ATSR peptide (n = 8), and 2.0 to 3.0 mM ATSR peptide (n = 4) compared to islands formed in media alone. *P = .1, **P = .004, ***P < .001 when compared to islands formed in media alone (C). Results are shown as mean ± SD.
