3 hydroxybutyric acid Article Gene Expression Profiling Metabolic Networks and Pathways Proteome Proteomics RNA sequencing Transcriptome cell isolation cell metabolism cell population crypt cell enzyme assay fluorescence activated cell sorting gene cluster gene expression gene expression profiling genetics glutamate synthase (NADH) liquid chromatography-mass spectrometry metabolic fingerprinting metabolism metabolite nicotinamide adenine dinucleotide nonhuman protein purification proteome proteomics stem cell transcriptome