Abstract: ObjectiveTo study the adaptive response induced by formaldehyde(FA)on eukaryocyte and its possible mechanism.MethodsAfter FA treatment,AlamarBlue reducing rate was observed to determine the cell proliferation.The total cellular proteins were separated using two-dimensional gel electrophoresis and visualized by sliver staining.Gels from different batches of control and FA-treated MRC-5 cells were analyzed for quantitative spot comparisons with the ImageMaster 2D platinum 5.0 software.The differentially expressed prorein spots were picked and digested in gel then identified by tandem mass spectrum.ResultsThe results of AlamarBlue reducing rate showed that low concentration of FA induced adaptive response on MRC-5 cells.Nineteen spots were changed significantly after FA treatment.Thirteen proteins were identified by peptide mass fingerprinting or peptide sequence analysis,including putative nucleoside diphosphate kinase,elongation factor 1-gamma,triosephosphate isomerase,60S acidic ribosomal protein P0,heat shock protein 75 kDa,similar to heat shock 70kD protein binding protein,annexin I,hypothetical protein FLJ 34423,microtubule-actin crosslinking factor 1,lamin B2, ATP synthase alpha chain,mitochondrial precursor,proteasome subunit alpha type 6.These identified proteins involved in energy metabolism,translation and RNA processing,protein folding,redox regulation,cell structure and cell signaling.ConclusionAdaptive response can be induced by low concentration of FA on MRC-5 cells and cellular adaptation is a complex process involving in a modulation of diverse cellular functions.