Next, the beads were resuspended in 100 l of biotinylated anti-mouse IgG(HϩL) (Vector Laboratories, Burlingame, CA) diluted 1:2,000 or biotinylated anti-rat IgG(HϩL) (Vector Laboratories) diluted 1:1,000 in 1% BSA-PBS and incubated on a plate shaker in the dark for 1 h at room temperature.