Functional specific roles of H ‐ ras and N ‐ ras . A proteomic approach using knockout cell lines

R as small GTP ases function as transducers of extracellular signals regulating cell survival, growth and differentiation. There are three major ras isoforms: H ‐, N ‐ and K ‐ R as. To improve the understanding of H ‐ and N ‐ R as protein signalling networks, we compared total proteome changes in mouse embryonic fibroblasts knock out for H ‐ ras and/or N ‐ ras , using proteomics tools combining 2DE, semi‐quantitative image analysis, in‐gel trypsin digestion and mass spectrometry. There are four up‐regulated proteins due to the loss of expression of H ‐ R as (including cyclin‐dependent kinase inhibitor 2 A ) and eight down‐regulated (including stress‐70 protein, dihydropyrimidinase‐related‐protein 3, heat shock cognate 71 kDa protein, tropomyosin beta chain, Rho GDP ‐dissociation inhibitor 1) and six up‐regulated proteins (e.g. leukocyte elastase inhibitor A , L ‐lactate dehydrogenase B chain, c‐ M yc‐responsive protein R cl, interleukin‐1 receptor antagonist protein) due to the loss of expression of both N ‐ and H ‐ R as. Most of these proteins are related to R as signalling in one way or another. Changes in expression of some of these proteins were further confirmed by W estern blot. This proteomic comparative analysis from loss of function of H ‐ and N ‐ R as knockout fibroblasts yields interpretable data to elucidate the differential protein expression, and contributes to evaluate the possibilities for physiological and therapeutic targets.