Western blot analysis of 6x-His Tag was performed by loading various amounts of E. coli lysate containing a multi-epitope tagged protein per well onto a 4-20% Tris-HCl polyacrylamide gel. Proteins were transferred to a PVDF membrane and blocked with 5% BSA/TBST for at least 1 hour. Membranes were probed with a 6x-His Tag polyclonal antibody (Product # PA1-983B-HRP) at a dilution of 1:500 for 1 hour at room temperature on a rocking platform and washed in TBS-0.1% Tween-20. Chemiluminescent detection was performed using Super Signal West Pico (Product # 34080).