Updated project metadata. MO3.13 is an immortal human-human hybrid cell line that express phenotypic characteristics of primary oligodendrocytes. It was created by fusing a 6-thioguanine-resistant mutant of the human rhabdomyosarcoma RD (cancer of skeletal muscle) with adult human oligodendrocytes by a lectin-enhanced polyethylene glycol procedure. In contrast to the tumor parent, MO3.13 expressed surface immunoreactivity for galactosyl cerebroside(GS) and intracellular immunoreactivity for myelin basic protein (MBP), proteolipid protein (PLP), and glial fibrillary acidic protein (GFAP). MO3.13 also exhibit the markers of immature oligodendrocytes GalC (galactosylceramidase) and CNPase. Upon differentiation, the MO3.13 cells have been also shown to express the MBP and MOG markers. Data analysis: Each MS raw file was processed using ProteoWizard for the generation of a MGF file. These were processed in SearchGUI, which runs the search engines Open Mass Spectrometry Search Algorithm (OMSSA) and X!Tandem against the UniProt human protein database (release 2013_08, 20,266 sequences).  Search parameters were: peptide and fragment ion mass accuracy 10 ppm and 0.5 Da, respectively; protein and peptide FDRs 1%; two miss cleavages; trypsin as enzyme; fixed modifications: cysteine carbamidomethylation; variable modifications: methionine oxidation. In order to generate one single proteome dataset of MO3.13, resulting data was processed in PeptideShaker.