Peptide Competition - Lysates prepared from A431 cells left unstimulated (1) or stimulated with 100 ng/mL PMA for 30 minutes at 37oC (2-5) were resolved by SDS-PAGE on a 10% polyacrylamide gel and transferred to PVDF. Membranes were blocked with a 3% non-fat dried milk-TBST buffer for one hour at room temperature and incubated with ab10695 for one hour at room temperature in a 1% non-fat dried milk-TBST buffer, following prior incubation with: no peptide (1, 2), the non-phosphopeptide corresponding to the immunogen (3), a generic phosphoserine-containing peptide (4), or, the phosphopeptide immunogen (5). After washing, membranes were incubated with goat F(ab’)2 anti-rabbit IgG HRP conjugate in 1% non-fat dried milk-TBST buffer, and bands were detected by chemiluminescence. The data show induction of ab10695 signal by PMA treatment and that the peptide corresponding to this site blocks the antibody signal, thereby demonstrating the specificity of the antibody. Peptide Co