SEARCH Articles Figures Tables Isotope isotopic labeling Isotope label Isotope stable isotopes Isotope-labeled proteins Isotope-labelled Isotopic labeling Isotopic labelled Isotopic labelling Isotopic labels Isotopical labeling Labeling quantitation Protein labels Protein quantitation Proteins labeling Proteins labelled Stable isotope Stable isotope labeled Stable isotope labeling Stable isotope labelling