The present invention relates to the use of post source decay (PSD) or collision induced dissociation (CID) direct tissue (DT) MALDI-TOF or DT-MALDI-TOF-TOF mass spectrographic identification of biological molecules in a tissue or cellular sample without the need for further protein extraction. This method provides for studying cells or tissues by direct tissue MALDI (DT-MALDI), thereby substituting in situ protein release for further protein extraction. Mass/intensity data was processed with Mascot.COPYRGT. software interrogation of the NCBI database. These results are proof of principle that DT-MALDI, combined with bioinformatics, can directly identify proteins in cells and tissues from their mass spectra.