Quantifications of proteins by Mass Spectrometry (MS) is a rapidly growing field with different quantitative tools at its disposal. The main goal of this study is to evaluate a stable isotope labelling method coupled to MS for the absolute quantification of proteins in the EGFR network, which plays an important role in cell differentiation and proliferation. This method uses Protein Epitope Signature Tags (PrETSs), representative of the target proteins, as quantification standards. We show that this method works for proteins in the EGFR network via a colorectal cancer cell line, but also highlight some of the important aspects of quantitative experiments in terms of data analysis and various sources of errors. A new cultivation medium has also been tested with success, and possible changes for a more streamlined quantification workflow is suggested.