This article has been withdrawn by the authors. We discovered an error after this manuscript was published as a Paper in Press. Specifically, we learned that the structures of glycans presented for the PD-L1 peptide were drawn and labeled incorrectly. We wish to withdraw this article and submit a corrected version for review.
Keywords: Absolute quantification; Biomarker: Prognostic; Clinical proteomics; Drug targets*; Glycosylation; Immunohistochemistry; Melanoma; Parallel reaction monitoring; immune checkpoint; immunotherapeutics.
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