Database Search, Protein Identification and Quantitation: Raw data were processed using Mascot Distiller v 2.1.1.0 (Matrix science). The resulting MS/MS dataset was exported to *mzdata data file format. We performed the peptide identification and assignment of partial post-translational modifications using an inhouse version of Mascot v. 2.2 (Matrix science). The datasets were searched against International Protein Index (IPI_human v. 3.29, 68161 sequences) using the following constraints: only tryptic peptides with up to two missed cleavage sites were allowed; 0.3-Da mass tolerances for MS and 0.1-Da mass tolerances for MS/MS fragment ions. Phosphorylation (STY), oxidation (M) was specified as variable modifications. Only unique peptide with scores higher than 25 was confidently assigned. When unique peptides were identified to multiple members of a protein family, proteins having the highest sequence coverage were selected from the Mascot search output result. To evaluate the protein identification falsepositive rate, we repeated the searches using identical search parameters and validation criteria against a random database (from the 68161 sequence). Relative quantification of peptides was performed by IDEAL-Q software [30, 31] .