The propagation of phosphorylation downstream of receptor tyrosine kinases is a key dynamic cellular event involved in signal transduction, which is often deregulated in disease states such as cancer. Probing phosphorylation dynamics is therefore crucial for understanding receptor tyrosine kinases' function and finding ways to inhibit their effects. MS methods combined with metabolic labeling such as stable isotope labeling with amino acids in cell culture (SILAC) have already proven successful in deciphering temporal phosphotyrosine perturbations. However, they are limited in terms of multiplexing, and they also are time consuming, because several experiments need to be performed separately. Here, we introduce an innovative approach based on 5-plex SILAC that allows monitoring of phosphotyrosine signaling perturbations induced by a drug treatment in one single experiment. Using this new labeling strategy specifically tailored for phosphotyrosines, it was possible to generate the time profiles for 318 unique phosphopeptides belonging to 215 proteins from an erlotinib-treated breast cancer cell line model. Hierarchical clustering of the time profiles followed by pathway enrichment analysis highlighted epidermal growth factor receptor (EGFR or ErbB1) and ErbB2 signaling as the major pathways affected by erlotinib, thereby validating the method. Moreover, based on the similarity of its time profile to those of other proteins in the ErbB pathways, the phosphorylation at Tyr453 of protein FAM59A, a recently described adaptor of EGFR, was confirmed as tightly involved in the signaling cascade. The present investigation also demonstrates the remote effect of EGFR inhibition on ErbB3 phosphorylation sites such as Tyr1289 and Tyr1328, as well as a potential feedback effect on Tyr877 of ErbB2. Overall, the 5-plex SILAC is a straightforward approach that extends sample multiplexing and builds up the arsenal of methods for tyrosine phosphorylation dynamics. Molecular & Cellular Proteomics 12: 10.1074/mcp.O113.027342, 3339-3349, 2013.The transmission of information in a cell is largely driven by protein phosphorylation (1, 2). It is used to convey a signal within the cell and modulate different biological outcomes such as transcription regulation or cytoskeleton rearrangement. The receptor tyrosine kinases represent key players at the plasma membrane interface because they operate as initiators of phosphorylation cascades (3, 4). Among the 58 receptor tyrosine kinases encoded by the human genome, the ErbB family members-composed of ErbB1 (also called epidermal growth factor receptor (EGFR)), 1 ErbB2, ErbB3, and ErbB4 -play a pivotal role because they control important processes such as cell differentiation, proliferation, and apoptosis (5). Deregulation of ErbB signaling networks is known to be connected to various diseases such as cancer (6, 7). Thus, the ErbB family members represent an important target class for understanding and curing disease-indeed, both small-molecule tyrosine kinase inhibitors (TKIs) and monoclonal a...