Synthesis of a photoswitchable cAMP analog by regioselective attachment of a tetra-ortho-fluorinated azobenzene moiety to regular cAMP provided the two isomers Z-7 and E-7 that are readily isomerized reversibly into each other by irradiation with visible light. E-7 and Z-7 show distinctly different capabilities to trigger the cAMP-dependent downstream signaling in CHO cells. This difference between the two isomers defines the molecular basis for controlling the intracellular cAMP signaling cascade by light from the outside without any cell or liquid handling. It is now possible to incubate adherent cells with a largely inactive cAMP mimic (Z-7) that is activated in situ by visible light (E-7). Different from photolysis of caged cAMP, the light intensities are rather low and do not harm the cells. Also different from photolysis, the in situ generation of cAMP is reversible so that kinetic details of the signaling cascades become easily assessable experimentally. Photolysis only provides the burst release of a given signaling molecule that will persist over time as it is only removable from the system by washing. Thus, the new cAMP mimic paves the way to analyze the response time of the cells to the presence or disappearance of cAMP with unprecedented time resolution. Not yet addressed in this study but subject of ongoing research is the local control of cAMP activation with microscopic precision on the stage of an optical microscope. Using microscopic illumination for photoswitching allows stimulating a limited number of cells within an extended cell monolayer while all cells outside of the field of view will be kept in resting state. This option of local control of cAMP release might become particularly useful for complex in vitro models like, for instance, organ-on-chips or even 3D tissue constructs, like tumoroids or organoids. The combination of (i) controlling the reversible activation of signaling molecules by visible light with (ii) a label-free, electrochemical detection of the cell response provides independent means for cell manipulation and cell observation. As we have shown previously, the two experimental approaches do not interfere with each other as their physical principles are orthogonal. With the electrodes for cell monitoring being deposited on the bottom of the wells while the light sources are placed on the top, the whole measurement unit fits into a regular cell culture incubator. With proper software control over the LEDs used for illumination as well as the impedance measurement unit, the whole experiment will be conducted without opening the incubator door in the future so that the resulting data will not be modulated by thermal effects or liquid handling.