Use of universal stable isotope labeling by amino acids in cell culture (SILAC)-based selected reaction monitoring (SRM) approach for verification of breast cancer-related protein markers.

Mass spectrometry-based proteomics facilitates high-throughput discovery of protein markers for diagnosis and treatment of breast cancer patients. Hundreds of putative prognostic and predictive markers are being identified every year, but only a very small proportion of them can be validated as clinically relevant markers. A quantitative and cost-efficient verification method is highly desirable to pick up real "nuggets" from the "sand." To fulfill these criteria, we previously introduced a stable isotope labeling by amino acids in cell culture (SILAC)-based selected reaction monitoring (SRM) approach for studying breast cancer-related protein markers. Here we describe a hands-on protocol of using this SILAC-SRM method for verification of breast cancer-related markers, which can also be used for verification of protein markers in other types of solid tumor tissues.