(Graph　Presented)　To　each　his　own:　An　addressable　electrochemical　device　consisting　of　orthogonally　arranged　rows　and　columns　of　electrodes　has　been　constructed　to　monitor　protein　expression　in　genetically　engineered　cells　at　the　single-cell　level.　The　response　based　on　redox　cycling　reflected　the　different　expression　levels　of　the　enzyme　from　individual　HeLa　cells　transfected　with　a　plasmid　vector　including　secreted　alkaline　phosphatase.　©　2009　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA.