protein array protein in situ array PSI-MI Protein In Situ Array is a method by which protein arrays are rapidly generated in one step directly from DNA, by cell-free protein expression and simultaneous in situ immobilisation at a surface. Individual genes or fragments are produce by PCR or RT-PCR depending on the source of genetic material using properly designed primers. The PISA is generated by cell-free protein synthesis using coupled transcription and translation to produce a tagged protein, the reaction being carried out on a surface to which the protein adheres as soon as it is synthesised. MI:0092 PISA pisa