Cells are the fundamental units of life forming all known living organisms, from single-cell prokaryotes to complex mammals. Biochemically, cells are the smallest unit capable of sustaining life. They exhibit the molecular complexity for a network of metabolic processes required to occur in an organized manner. To maintain a balanced physiological state, various regulatory mechanisms have evolved. Signaling cascades work together to control biochemical reactions, allowing the living system to maintain itself away from thermodynamic equilibrium. Intense scientific effort has been made to unravel these signaling cascades inside living organisms. Among others, the G-protein coupled receptors (GPCRs) and their downstream signaling cascades have been addressed extensively due to their involvement in many severe diseases. For instance, GPCRs are targeted by approximately 35% of prescription pharmaceuticals, emphasizing the relevance of their signal transduction cascades for pharmacology. For example, the activation of the 𝛽 -adrenergic receptor by the hormone adrenaline on the extracellular side triggers a complex signal transduction mechanism involving several enzymes such as adenylyl cyclase (AC), protein kinase A (PKA), or the cyclic nucleotide adenosine 3',5'-cyclic monophosphate (cAMP). cAMP is the central intracellular second messenger in this cascade, forwarding the incoming signal to further downstream effectors of the cell. Since cAMP is involved in controlling cyclic nucleotide-gated ion channels, exchange-proteins activated by cAMP (EPAC), Popeye domain-containing proteins, and the enzyme PKA, it is one of the most intensely studied second messengers. Among other functions, PKA controls metabolic pathways, such as the catabolism of glycogen or fatty acids. Acting as a connecting link between the extracellular stimulus perceived by the GPCR and further downstream effectors, cAMP not only forwards the incoming signal, but its biosynthesis in multiple copies also denotes an amplification step. As a result, cells typically exhibit an extraordinary sensitivity towards extracellular stimuli such as adrenaline. First, it was assumed that cAMP concentrations are similar across the cytoplasm. However, cAMP is hydrolyzed by cAMPspecific phosphodiesterases (PDEs), which are targeted to specific locations within the cell. Consequently, cAMP levels are not uniform inside the cell, which is the fundamental clue to understand why cAMP can mediate such a plethora of different physiological processes in one cell. It is this nonhomogeneous distribution of cAMP and the consequences arising thereof that have not yet been fully unraveled. Thus, to better understand the complex signal transduction cascade mediated via the second messenger cAMP, full spatial and temporal control of its intracellular activity by photochromic derivatives promises new insights not available by other means. One commonly used and commercially available cAMP derivative is 8-(4-chlorophenylthio)-cAMP (8-CPT-cAMP), which is lipophilic enough to penetrate the cell membrane. Inside the cell, it mimics cAMP, triggers the PKA, and activates the cAMPrelated signaling pathway. Adding this cAMP derivative to the culture medium is typically sufficient to induce the signaling cascade, but this method has significant drawbacks. Firstly, adding the 8-CPT-cAMP to the bulk prevents precise spatial targeting of individual cells or cell clusters in a tissue-like cell culture model. Secondly, activation of the signaling cascade is permanent unless the substance is hydrolyzed or manually washed out from the cells under study. This results in an irreversible release of the biological response so that it becomes impossible to monitor the dynamic response of cells to the signaling impulse.