Western blot analysis is shown using Affinity Purified anti-Huntingtin pS421 antibody to detect endogenous protein present in an unstimulated human PC-3 whole cell lysate (arrowhead). Comparison to a molecular weight marker indicates a band of ~190 kDa corresponding to truncated human Huntingtin protein. The blot was incubated with a 1:1,000 dilution of the antibody at room temperature followed by detection using standard techniques. Personal communication,