PMC

Identification of the peptide VC*SQYAAYGEK from vitamin D-binding protein by MS/MS.

Quantification of vitamin D-binding protein through the ICAT-labeled parent ion signals of the peptide VC*SQYAAYGEK.

Using the ProICAT bioinformatics program, 353 peptides were identified. Approximately equal numbers of proteins were up- versus down-regulated.

Schema of ICAT analysis performed using a Cleavable ICAT Reagent Kit (Applied Biosystems, Foster City, CA) according to the manufacturer's guidelines, with some modifications. Avidin Affinity refers to the Avidin Affinity Cartridge kit (Applied Biosystems, Foster City, CA)

Western blot analysis of independent NAF sample set. The relative difference in vitamin D-binding protein expression in the pooled samples of NAF from healthy volunteers versus NAF from women with early-stage breast cancer was two-fold (P = 0.04; standard error = 9703.7 (solid bars). Individual NAF specimens showed variation in vitamin D-binding protein expression among both healthy volunteers and women with early-stage breast cancer (dotted bars). Menopausal status did not affect expression of vitamin D-binding protein in NAF.