iTRAQPak: an R based analysis and visualization package for 8-plex isobaric protein expression data.

The field of high throughput proteomics has spawned a number of mass spectrometry-based technologies, which enable the quantitative analysis of protein expression. One of these technologies is iTRAQ (trademarked by Applied Biosystems), which through the use of isobaric tags, enables the quantitation of up to eight complex protein samples in a single multiplexed analysis. Isobaric tagging methods are emerging as an important tool to study protein expression dynamics. In this report, we describe iTRAQPak, a free software package developed in the R statistical and visualization environment that can be applied to the analysis of 8-plex expression data. The utility of this package is demonstrated through its application to the analysis of 8-plex iTRAQ protein expression data obtained from cerebrospinal fluid samples from Alzheimer's disease subjects involved in a Phase I drug trial.