Optimization of cAMP activity using the inkjet-printing method. (A) Represents printing order. (B) FRET signals were acquired with cAMP, and their respective images were illustrated as: 1. monochrome image; 2. fluorescent dye color image; 3. intensity profile of three different regions; and 4. percentage intensity profile of three regions. (C) FRET signals were acquired without cAMP, and their respective images were shown as: 1. monochrome image; 2. fluorescent dye color image; 3. intensity profile of three different regions; and 4. percentage intensity profile of three regions. (D) Fluorescence signal generated on a single spot was measured. The graph illustrates the individual fluorescence signal produced with and without cAMP by three different regions/spot areas.