Exemplary comparative linear-MALDI-TOF mass spectra of proteins in 40% (v/v) acetonitrile eluted reversed-phase SPE fractions of 0.4 M potassium chloride eluted anion-exchange fraction, derived from DDF cytosolic extracts of six samples of cultured human Neuro-2A cells. Proteins in fractions were directly cospotted with alpha-cyano-4-hydroxy-cinnamic acid matrix. This data serves to show the high between sample extract precision with which some proteins were recovered and could be analysed.