DNA sequencing has advanced to a state that permits studying the genomes of individual patients as nearly a matter of routine. Towards analysing a tissue's protein content in a similar manner, we established a method for the production of microarrays that represent full-length proteins as they are encoded in individual specimens, exhibiting the particular variations, such as mutations or splice variations, present in these samples. From total RNA isolates, each transcript is copied to a specific location on the array by an on-chip polymerase elongation reaction, followed by in situ cell-free transcription and translation. These microarrays permit parallel analyses of variations in protein structure and interaction that are specific to particular samples.