Pre-clearance of OPH or inhibition by DFP ablates OPH activity bands. A) LNCaP and RWPE-1 lysates were separated by 6% n-PAGE. The gel was pre-incubated in phosphate buffer or phosphate buffer containing 50 μM DFP for 30 min. Esterase activity bands were visualized with S-ANAA and Fast Blue RR salt. B) LNCaP lysates containing 120 μg of protein were pre-cleared with protein A beads or anti-OPH antibody bound to protein A beads. The collected lysates were separated by 6% n-PAGE and the esterase activity visualized with S-ANAA and Fast Blue RR salt.