(A) We have used a new, superresolution PKA activity reporter FLINC-AKAR to reveal that PKA activity is organized into discrete clusters along the plasma membrane, which likely correspond to clusters of AKAP-assembled molecular signalosomes. (B) A superresolution image of a representative HeLa cell expressing FLINC-AKAR, illustrating clear activity hotspots following PKA stimulation (magnified in inset). Scale bar, 10 μm (inset, 1 μm).