Role of H2B in Matrigel invasion and cell migration. (A,B) RAW 264.7 cells (5 × 10⁴) were either pretreated with anti-uPA (0.5 μg/mL; American Diagnostica, Greenwich, CT), anti-H2B Fab, or nonimmune rabbit Fab or left untreated for 30 minutes. Cells were loaded into the upper portion of Matrigel-coated chambers, together with Plg, and in the absence or presence of aprotinin (50 U/mL; Calbiochem, San Diego, CA), EACA, or TXA, and were allowed to migrate toward MCP-1 in the lower chamber. The invading cells were quantified as described in “Cell invasion and cell migration.” The data are expressed as the means plus or minus SD of 2 independent experiments, and statistical significance was determined by a Student t test. Note that EACA and TXA inhibited 90% and 84% of Plg-dependent RAW 264.7 cell transmigration, respectively, and that anti-H2B Fab inhibited the response by 70% (B). (C,D) RAW 264.7 cells were either pretreated with anti-H2B Fab or nonimmune Fab or left untreated. Cells were loaded into the upper chambers with Plg, in the absence or presence of EACA or TXA, and with MCP-1 in the lower chambers. The membrane separating the upper and lower chamber was uncoated. Migrated cells were quantified as in panels A and B. The data are expressed as the means plus or minus SD of 2 independent experiments and statistical significance was determined by a Student t test.