A bead-based multiplex sandwich immunoassay to assess the abundance and posttranslational modification state of β-catenin.

A system-wide analysis of cell signaling involves detecting and quantifying a range of proteins and their posttranslational modification states in the same cellular sample. We propose a protocol for a miniaturized, bead-based array and describe its efficiency in characterizing the different forms and functions of β-catenin. The protocol provides detailed instructions for cell culture and bead array assays that enable insights into complex networks at the systems level.