TP53 activity in the over-expression lysate (LY400186) was measured in a colorimetric DNA-binding assay. Double-stranded oligonucleotide containing the p53 consensus DNA-binding sequence was incubated with dilutions of the over-expression lysate and TP53 bound to the oligo was captured onto the surface of a microtiter plate. After washing, bound TP53 was detected with an anti-p53 primary antibody followed by an HRP-labeled secondary antibody. After initial color development, the reaction was quenched and the color intensity was measured at 450nm. Overexpression cell lysates are prepared from HEK293T cells transfected with RC200003 using transfection reagent MegaTran 2.0 (Cat# TT210002).