Protein Quantification may solve several problems such as...1)
<In vivo>
1.Inter-organ difference in proteinabundance.
2.Differences in functional proteinlocalization in various organs and their impact on pharmacokinetics, efficacy,and drug toxicity.
3.Assay system of ADMET and efficacy basedon differences in functional protein abundance in organs.
4.Characteristics of transgenic orgene-knockout animals based on the expression levels of a target protein andother non-target proteins.
5.Consistency between the characteristicsof xenograft-transplanted animals and human diseases.
6.Inter-colony, inter-strain, inter-sex,inter-species, inter-racial, inter-disease, and intra-disease differences inthe expression levels of functional proteins.
7.Impact of circadian rhythm anddeveloping/aging on functional proteins.
8.Prediction of ADMET and efficacy of drugsin animals and humans, including the diseased state, based on the absolutelevels of functional proteins.
9.Determinant factors that can affectinter-individual differences in ADMET, drug efficacy, and their impact onpersonalized medicine.
10.Suitable choice of molecular target-baseddrugs based on the absolute levels of target proteins in a drug-targetingorgan.

In vitro>
1.Protein abundance in the plasma membraneand/or organelles, including the cytoplasm.2.Differential protein expression in theorgan from which the cells originated.
3.Differential protein expression in thedifferent sides of membrane vesicles.
4.Differential protein expression ofcellular characteristics under various cell culture conditions such asco-culture, conditioned medium and passage number.
5.Alteration of cellular characteristics atvarious stages of differentiation.
6.Expression level of target protein(s)over-expressed in cells by transfection of the corresponding gene.
7.Expression level of an endogenousprotein(s) to select a host cell line for the transfection of an exogenous geneand to validate the up-regulation and/or down-regulation of functionallyrelated proteins in the cells after transfection of an exogenous gene.
8.Expression level of target proteinsgenerated by an artificially transfected exogenous chromosome, such as one froma different species of animal, in the cells.
9.Cellular characterization of xenograft tissues before and after their transplantation into in vivo animals.

1) Cited from Fluids and Barriers of the CNS2013, 10:21