MRP14^-/- mice show decreased migration rates of neutrophils during wound healing. (A) Transendothelial migration rates of MRP14^+/+ and MRP14^-/- granulocytes through a monolayer of bEND5 endothelial cells. Granulocytes were either left untreated or preincubated with arsenite for 30 minutes prior to transendothelial migration to activate p38 MAPK. Bars represent n-fold induction of transmigration rates by arsenite stimulation compared to unstimulated control cells of the appropriate mouse strain. ^* indicates a statistically significant difference (P ≤ .05). Mean and SD of 5 independent experiments are shown. (B) Mice were wounded as described in “Materials and methods.” The extent of wound closure was determined morphometrically on histologic sections prepared from 5-day old wounds of MRP14^-/- mice and MRP^+/+ control littermates (8 wounds each). MRP14^-/- mice show a significantly accelerated rate of wound closure as compared to MRP14^+/+ mice (P ≤ .02). (C-F) Paraffin sections of 5-day-old murine wounds were stained with antibodies directed against cytokeratin 6 (K6, red), cytokeratin 10 (K10, blue), and the granulocyte-specific antigen Ly6G (green), followed by Cy3-, Cy5-, and Cy2-conjugated secondary antibodies, respectively. Panels C and E present sections of MRP14^+/+ mice; D and F, sections of MRP14^-/- mice at lower (C-D) or higher (E-F) magnifications (bars represent 100 μm). MRP14^-/- mice show a significantly lower number of Ly6G⁺ granulocytes in their granulation tissue. Figures shown are representative for 8 animals from each genotype analyzed.