Focus issue: Tackling reproducibility and accuracy in cell signaling experiments.

With contributions from the Board of Reviewing Editors and the Chief Scientific Editor, Science Signaling highlights some common concerns surrounding reproducibility and issues related to appropriate methodological considerations for accurately quantifying and then modeling regulatory phenomena. Specific topics include sources of error, understanding biological "n" and the application of appropriate statistical analyses, quantitative Western blotting, quantitative mass spectrometry-based proteomics, and parameterization for establishing quantitative models of cellular networks.