Thereafter, the plate was tapped dry and blocked with 100 l/well of 0.25% bovine serum albumin (BSA), 0.05% Tween 20 (Sigma) in 0.01 M PBS, pH 7.2 at 37 ◦C for 30 min. Consequently, the plate was similarly washed prior to adding 100 l of undiluted MoAb 2F9 and diluted MoAb 2F9 at 1:10, 1:100, 1:500 and 1:1000, and incubated at 37 ◦C for 2 h. After washing, the plate was incubated with 100 l/well of horseradish peroxidase conjugated goat antimouse immunoglobulin (Sigma–Aldrich Inc.) at 1:6000 dilution in the blocking solution at 37 ◦C for 1 h.